Wo r k in gP ap e r E conom i cS e r i e s1 4–2 5 Ap r i l2 0 1 5 I S SN2 3 4 0 5 0 3 1 D ep a r t am en tod eE conom í a Un i v e r s id adC a r lo sI I Id eM ad r id C/ M ad r id ,1 2 6 ,2 8 9 0 3G e t a f e( Sp a in ) F a x( 3 4 )9 1 6 2 4 9 8 7 5 “ANALTERNAT IVETOF IELD -NORMAL IZAT IONINTHEAGGREGAT ION OF HETEROGENEOUSSC IENT IF ICF IELDS ” b An ton ioP e r i an e s -Rod r i g u e za andJ a v i e rR u i z -C a s t i l lo a D ep a r t am en tod eB ib l io t e conom í ayDo c um en t a c ión ,Un i v e r s id adC a r lo sI I I ,SC Im a goR e s e a r ch G ro up b D ep a r t am en tod eE conom í a ,Un i v e r s id adC a r lo sI I I Ab s t r a c t.Apo s s ib l eso l u t iontoth ep rob l emo fa g g r e g a t in gh e t e ro g en eo u sf i e ld sinth ea l l s c i en c e s c a s er e l i e sonth eno rm a l i z a t iono fth er awc i t a t ion sr e c e i v e db ya l lp ub l i c a t ion s .Inth i sp ap e r ,w e s t ud yana l t e rn a t i v eso l u t ionth a tdo e sno tr e q u i r ean yc i t a t ionno rm a l i z a t i on .Pro v id e don eu s e ss i z e ands c a l e ind ep end en tind i c a to r s ,th ec i t a t ionimp a c to fan yr e s e a r chun i tc anb ec a l c u l a t e da sth e a v e r a g e(w e i gh t e db yth ep ub l i c a t iono u tp u t )o fth ec i t a t ionimp a c tth a tth eun i ta ch i e v e sina l lf i e ld s . Th etwoa l t e rn a t i v e sa r eco n f ron t e d wh enth er e s e a r cho u tp u to fth e5 0 0un i v e r s i t i e sinth e2 0 1 3 e d i t iono fth e CWT SL e id en R an k in gi se v a l u a t e du s in gtwoc i t a t ionimp a c tind i c a to r sw i thv e r y d i f f e r en tp rop e r t i e s .W eu s ea l a r g eW ebo fS c i en c ed a t a s e tcon s i s t in go f3 . 6m i l l iona r t i c l e sp ub l i sh e d inth e2 0 0 5 2 0 0 8p e r iod ,andac l a s s i f i c a t ions y s t emd i s t in g u i sh in gb e tw e en5 , 1 1 9c l u s t e r s .Th em a in twof ind in g sa r ea sfo l low s .F i r s t l y ,d i f f e r en c e sinp rod u c t ionandc i t a t ionp r a c t i c e sb e tw e enth e3 , 3 3 2 c l u s t e r sw i th mo r eth an2 5 0p ub l i c a t ion sa c co un tfo r2 2 . 5%o fth eo v e r a l lc i t a t ionin e q u a l i t y .A f t e r th es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r ewh e r ec l u s t e rm e anc i t a t ion sa r eu s e da sno rm a l i z a t ion f a c to r s ,th i sf i g u r ei sr e d u c e dto4 . 3% .S e cond l y ,th ed i f f e r en c e sb e tw e enth eun i v e r s i t yr an k in g s a c co rd in gtoth etwoso l u t ion sfo rth ea l l s c i en c e sa g g r e g a t ionp rob l ema r eo fasm a l lo rd e ro f m a gn i t ud efo rbo thc i t a t ion imp a c t ind i c a to r s . A cknow l edg em en t s. Th i s i sth eth i rdv e r s iono fap ap e rw i thth es am et i t l ep ub l i sh e d inth i ss e r i e s in D e c emb e r,2 0 1 4 ,andF eb r u a r y ,2 0 1 5 .Th i sr e s e a r chp ro j e c tb u i ld sone a r l i e rwo r ks t a r t e db yJ a v i e r R u i z -C a s t i l lod u r in gar e s e a r chv i s i ttoth eC en t r efo rS c i en c eandT e chno lo g yS t ud i e s(CWT S )o f L e id en Un i v e r s i t y .Th ea u tho r sg r a t e f u l l ya c know l e d g eCWT Sfo rth eu s eo fi t sd a t a.R u i z -C a s t i l lo a c know l e d g e sf in an c i a ls uppo r tf rom th e Sp an i sh MEC th ro u gh g r an t ECO 2 0 1 12 9 7 6 2 . Con v e r s a t ion sw i th An ton io V i l l a r ,P e d ro A lb a r r án ,andL udo W a l tm ana r ed e ep l yapp r e c i a t e d .A l l r em a in in gsho r t com in g sa r eth ea u tho r s ’so l e r e spo n s ib i l i t y . 1 I .INTRODUCT ION A si sw e l lknown ,th ecomp a r i sono fth ec i t a t ionimp a c to fr e s e a r chun i t si sp l a g u e dw i th ob s t a c l e so fa l lso r t s .Fo ro u rp u rpo s e sinth i sp ap e r ,i ti su s e f u ltod i s t in g u i shb e tw e enth efo l low in g th r e eb a s i cd i f f i c u l t i e s . ( i )Howc anw ecomp a r eth ec i t a t iond i s t r ib u t ion so fr e s e a r chun i t so fd i f f e r en t s i z e se v eni fth e ywo r kinth es am ehomo g en eo u ss c i en t i f i cf i e ld ?Fo re x amp l e ,howc anw ecomp a r e th eo u tp u to fth el a r g eE conom i c sd ep a r tm en ta tH a r v a rdUn i v e r s i t yw i thth eo u tp u to fth er e l a t i v e l y sm a l lE conom i c sd ep a r tm en ta tJohn s Hop k in s ? Th en e x ttwod i f f i c u l t i e sh a v etodo w i thth e h e t e ro g en e i t yo fs c i en t i f i cf i e ld s :th ew e l lknownd i f f e r en c e sinp rod u c t ionandc i t a t ionp r a c t i c e s m a k e si timpo s s ib l e tod i r e c t l ycomp a r eth er awc i t a t ion sr e c e i v e db ya r t i c l e sb e lon g in gtod i f f e r en t f i e ld s .G i v enac l a s s i f i c a t ions y s t em ,th a ti s ,ar u l efo ra s s i gn in gan ys e to fa r t i c l e stoan umb e ro f s c i en t i f i cf i e ld s ,f i e ldh e t e ro g en e i t yp r e s en t sth efo l low in gc l a s s i ch ind r an c e sinth ee v a l u a t iono f r e s e a r chun i t s ’p e r fo rm an c e .( i i ) Howc an w ecomp a r eth ec i t a t ionimp a c to ftwor e s e a r chun i t s wo r k in gind i f f e r en tf i e ld s ?Fo re x amp l e ,howc anw ecomp a r eth ec i t a t ionimp a c to fM ITin O r g an i c Ch em i s t r yw i thth ec i t a t ion imp a c to fO x fo rdUn i v e r s i t y inS t a t i s t i c sandP rob ab i l i t y ?F in a l l y ,( i i i )how c anw ecomp a r eth ec i t a t ion imp a c to ftwor e s e a r chun i t st a k in g in toa c co un tth e i ro u tp u t ina l lf i e ld s ? Fo re x amp l e ,howc anw ecomp a r eth ec i t a t ionimp a c to fM ITand O x fo rdUn i v e r s i t yinwh a tw ec a l l th ea l l s c i e n c e sc a s e ? A si sw e l lknown ,th eso l u t iontoth ef i r s t twop rob l em sr e q u i r e ss i z e -ands c a l e ind ep end en t c i t a t ion imp a c t ind i c a to r s . W ew i l lr e f e rto ind i c a to r sw i thth e s etwop rop e r t i e sa sa dm i s s i b l eind i c a to r s . G i v enanadm i s s ib l e ind i c a to r , inth i sp ap e rw ea r econ c e rn e dw i thth etwot yp e so fso l u t ion sth a tth e th i rdp rob l emadm i t s .F i r s t l y ,th ep rob l emc anb eso l v e dintwos t ep s . On ef i r s tu s e ssom eso r to f no rm a l i z a t ion p ro c e d u r eto m a k eth ec i t a t ion so fa r t i c l e sina l lf i e ld sa tl e a s tapp ro x im a t e l y comp a r ab l e .Th en ,on eapp l i e sth ec i t a t ionind i c a to rtoe a chun i t ’ sno rm a l i z e dc i t a t iond i s t r ib u t ion . S e cond l y ,con s id e rth eT op1 0%ind i c a to ru s e dinth econ s t r u c t iono fth ein f l u en t i a lL e id enand 2 1 SC Im a g or an k in g s . Inth eL e id enR an k in gth i sind i c a to ri sd e f in e da s“ T h ep r o p o r t i o no fp u b l i c a t i o n so fa u n i v e r s i t yt h a t ,c om p a r e dw i t ho t h e rs im i l a rp u b l i c a t i o n s ,b e l o n gt ot h et o p1 0%m o s t f r e q u e n t l yc i t e d…P u b l i c a t i o n sa r e c o n s i d e r e ds im i l a ri ft h e yw e r ep u b l i s h e di nt h es am ef i e l da n dt h es am ep u b l i c a t i o na n di ft h e yh a v et h es am ed o c um e n t 2 t y p e ”(W a lm ane ta l . ,2 0 1 2 a ) . No t eth a tth i sw a yo fcomp u t in gth i sp a r t i c u l a rind i c a to rinnth ea l l 3 s c i en c e sc a s edo e sno tr e q u i r ean yk indo fp r io rc i t a t ionno rm a l i z a t ion . Fo ro u rp u rpo s e s ,i ti su s e f u l tov i ewth i sp ro c e d u r ea sth ea v e r a g e(w e i gh t e db yth ep ub l i c a t iono u tp u t )o fth eun i t ’ sT op1 0% p e r fo rm an c eine a chf i e ld .W eno t eth a tth i simpo r t an tp r e c e d en tc anb ee x t end e dtoa n yadm i s s ib l e ind i c a to r .Th u s ,g i v enac l a s s i f i c a t ions y s t emandanadm i s s ib l ec i t a t ion ind i c a to r ,w ec ancomp u t eth e c i t a t ionimp a c to far e s e a r chun i tinth ea l l s c i en c e sc a s ea sth eapp rop r i a t ew e i gh t e da v e r a g eo fth e un i t ’ sc i t a t ion imp a c t ine a chf i e ld .Ind ep end en t l yo fth econ c ep t u a l in t e r e s to fth i sp ropo s a l ,w em u s t comp a r eth econ s e q u en c e so fadop t in gi tv e r s u sth e po s s ib i l i t yo ffo l low in ga no rm a l i z a t ion p ro c e d u r e . In t u i t i v e l y ,th eb e t t e rth ep e r fo rm an c eo fth e no rm a l i z a t ion p ro c e d u r eine l im in a t in gth e comp a r ab i l i t yd i f f i c u l t i e sa c ro s sf i e ld s ,th esm a l l e rth ed i f f e r en c e sw i l lb eb e tw e enth etwoapp ro a ch e s . U s in ga m e a s u r in gf r am ewo r kin t rod u c e dinC r e spoe ta l .( 2 0 1 3 ) ,r e c en tr e s e a r chh a se s t ab l i sh e dth a t d i f f e r en tso u r c e(o rc i t in g s id e )andt a r g e t(o rc i t e d s id e )no rm a l i z a t ionp ro c e d u r e sp e r fo rmq u i t ew e l l ine l im in a t in g mo s to fth ee f f e c tino v e r a l lc i t a t ionin e q u a l i t yth a tc anb ea t t r ib u t e dtod i f f e r en c e sin p rod u c t ionandc i t a t ionp r a c t i c e sb e tw e enf i e ld s(W a l tm an&V anE c k ,2 0 1 3 ,C r e spoe ta l . ,2 0 1 3 ,2 0 1 4 , andL ie ta l . ,2 0 1 3 ) . Th e r e fo r e,w ee xp e c tth a tth ed i f f e r en c e sb e tw e enth etwoapp ro a ch e sfo rso l v in g th ea l l s c i en c e sa g g r e g a t ionp rob l em wo u ldb eo fasm a l lo rd e ro fm a gn i t ud e .How e v e r,th i si san 1S C Im a goi s ar e s e a r chg ro upf romth eC o n s e j oS u p er i o rd eI n v e s t i g a c i o n e sC i e n t í f i c a s ,Un i v e r s i t yo fG r an ad a ,E x t r em ad u r a ,C a r lo s I I I(M ad r id )and A l c a l ád eH en a r e sinSp a in .T h eSC Im a g oI n s t i t u t i o n sR a nk i n g s( S IR ;www . s c im a go i r . com)i sab ib l iom e t r i c r an k in go fr e s e a r ch in s t i t u t ion sba s edonE l s e v i e r ’ sS cop u sd a t ab a s e . 2As im i l a rd e f in i t ioni sapp l i edinth eSC Im a gor an k in g(Bo rnm ann e ta l . ,2 0 1 2 ) ,a sw e l la sinth eInC i t e sso f tw a r e( s e e ‘p e r c en t i l eIs ub j e c ta r e a inh t tp :// i n c i t e s . i s i know l ed g e . com/ common/h e lp/h_ g lo s s a r y .h t lm ) . 3N a t u r a l l y ,e v e r y th in gth a tw es a yfo rth ea l ls c i en c e sc a s ec anb ee q u a l l yapp l i eda to th e ra g g r e g a t ionl e v e l s ,a sinth ec a s e o fa g g r e g a t in ga r t i c l e sin O r g an i cCh em i s t r y ,Ino r g an i cCh em i s t r y ,Ch em i c a lEn g in e e r in g ,ando th e rr e l a t eds ub f i e ld sin to th ed i s c ip l in eo fCh em i s t r y . 3 emp i r i c a lq u e s t ionth a th a sn e v e rb e enin v e s t i g a t e d b e fo r e . Tocon f ron tth i sq u e s t ion , inth i sp ap e rw e cond u c tth efo l low in ge x e r c i s e . •R u i z -C a s t i l lo& W a l tm an( 2 0 1 5 )app l yth ep ub l i c a t ion l e v e la l go r i thm i cm e thodo lo g y in t rod u c e d b yW a l tm an &V anE c k( 2 0 1 2 )toa W ebo fS c i en c e(Wo Sh e r e a f t e r )d a t a s e tcon s i s t in go f9 . 4m i l l ion p ub l i c a t ion sf rom th e2 0 0 3 2 0 1 2p e r iod . Th i si s don ea lon gas e q u en c eo ftw e l v eind ep end en t c l a s s i f i c a t ions y s t em sine a cho fwh i chth es am es e to fp ub l i c a t ion si sa s s i gn e dtoanin c r e a s in gn umb e r o fc l u s t e r s .Inth i sp ap e r ,w eu s eth ec l a s s i f i c a t ions y s t emr e comm end e dinR u i z -C a s t i l lo & W a l tm an ( 2 0 1 5 ) ,con s i s t in go f5 , 1 1 9c l u s t e r s .Fo rth ee v a l u a t iono fr e s e a r chun i t s ’c i t a t ionimp a c t ,w efo c u son th e3 . 6m i l l ionp ub l i c a t ion sinth e2 0 0 5 2 0 0 8p e r iod ,andth ec i t a t ion sth e yr e c e i v ed u r in gaf i v e -y e a r c i t a t ionw indowfo re a chy e a r inth a tp e r iod . •O u rr e s e a r chun i t sa r eth e5 0 0un i v e r s i t i e sinth e2 0 1 3e d i t iono fth eCWT SL e id enR an k in g (W a l tm ane ta l . ,2 0 1 2 a ) .W ean a l y z eth eapp ro x im a t e l y2 . 4m i l l iona r t i c l e s– abo u t6 7%o fth eto t a l –fo r wh i cha t l e a s ton ea u tho rb e lon g stoon eo fth e s eun i v e r s i t i es .W eu s eaf r a c t ion a lco un t in gapp ro a chto so l v eth ep rob l emo fth ea s s i gnm en to fr e spon s ib i l i t yfo rp ub l i c a t ion sw i ths e v e r a lco a u tho r swo r k in g in d i f f e r en tin s t i t u t ion s . Th eto t a ln umb e ro fa r t i c l e s co r r e spond in gtoth e5 0 0 un i v e r s i t i e si s app ro x im a t e l y1 . 9m i l l iona r t i c l e s– abo u t5 0%o fth eto t a l . • W ee v a l u a t eth ec i t a t ionimp a c to fe a chun i v e r s i t yu s in gtwoadm i s s ib l eind i c a to r s .F i r s t l y ,th e Top1 0%ind i c a to ra l r e ad ym en t ion e d .S e cond l y ,on ech a r a c t e r i s t i co fth i sind i c a to ri sth a ti ti sno t mono ton i cinth es en s eth a ti ti sin v a r i an ttoan yadd i t ion a lc i t a t ionth a tah i gh imp a c ta r t i c l em i gh t r e c e i v e .Con s e q u en t l y ,w eb e l i e v eth a t i t i s in t e r e s t in gtou s eas e cond ind i c a to rpo s s e s s in gth i sp rop e r t y . In p a r t i c u l a r ,w es e l e c ta m emb e ro fth eFo s t e r ,G r e e r ,and Tho rb e c k e(FGT h e r e a f t e r )f am i l y , in t rod u c e dinA lb a r r áne ta l .( 2 0 1 1 a ) .W eapp l yth i sind i c a to rtoth es e tfo rm e db yth e1 0%o fth e mo s t h i gh l yc i t e dp ub l i c a t ion s inth ewo r ld ,r e f e r r e dtoa sth es e to fh i gh imp a c ta r t i c l e s. 4 •L ie ta l .( 2 0 1 3 )ind i c a t eth a tth eb e s ta l t e rn a t i v eamon ga w id es e to ff i e ld -no rm a l i z a t ion p ro c e d u r e si sth etwo -p a r am e t e rs y s t emd e v e lop e dinR ad i c c i &C a s t e l l ano( 2 0 1 2 ) .4 How e v e r ,d i f f e r en t r e s u l t sind i c a t eth a tth es t and a rd ,on e -p a r am e t e rf i e ld -no rm a l i z a t ionp ro c e d u r e ,in wh i chno rm a l i z e d c i t a t ions co r e sine v e r yf i e lda r ee q u a ltoth eo r i g in a lr awc i t a t ion sd i v id e db yth ef i e ld m e anc i t a t ion , e xh ib i t sagoodp e r fo rm an c e(R ad i c ch ie ta l . ,2 0 0 8 ,C r e spoe ta l . ,2 0 1 3 ,2 0 1 4 ,L ie ta l . ,2 0 1 3 ,andR u i z C a s t i l lo ,2 0 1 4 ) .G i v eni t ss imp l i c i t yandgoodp e r fo rm an c e ,inth i sp ap e rw eadop tth i sp ro c e d u r einth e so l u t iontoth ea l l s c i en c e sa g g r e g a t ionp rob l em . • Anind i c a to ri ss a idto b eadd i t i v e l yd e compo s ab l ei f ,fo ran yp a r t i t ion o fac i t a t ion d i s t r ib u t ionin toan umb e ro fd i s jo in ts ub g ro up s ,th ec i t a t ionimp a c to fth een t i r ed i s t r ib u t ionc anb e e xp r e s s e da sth ea v e r a g e(w e i gh t e db yth es ub g ro up s ’o u tp u t )o fth es ub g ro up s ’c i t a t ionimp a c t .A s w i l lb es e en b e low ,th ef a c tth a t bo th o fo u rind i c a to r s po s s e s sth i sp rop e r t yf a c i l i t a t e s th e comp a r ab i l i t yo fth etwoso l u t ion stoth ea l l s c i en c e sa g g r e g a t ionp rob l emth a tcon s t i t u t e sth em a in a imo fth ep ap e r . • W ep r e s en ttwot yp e so fr e s u l t s .F i r s t l y ,w ea s s e s sth ep e r fo rm an c eo fth es t and a rdf i e ld no rm a l i z a t ionp ro c e d u r e inf a c i l i t a t in gth ecomp a r ab i l i t yo fth ec i t a t ion sr e c e i v e db ya r t i c l e sb e lon g in g tod i f f e r en tc l u s t e r s .S e cond l y ,w ea s s e s sth econ s e q u en c e so fadop t in gth etwoso l u t ion stoth ea l l s c i en c e sa g g r e g a t ionp rob l emb ycomp a r in gth eco r r e spond in gun i v e r s i t yr an k in g sa c co rd in gtoth e twoadm i s s ib l ec i t a t ion imp a c t ind i c a to r s . •Th e two m a inf ind in g sa r eth efo l low in g .F i r s t l y ,d i f f e r en c e sinp rod u c t ionandc i t a t ion p r a c t i c e sb e tw e en3 , 3 3 2c l u s t e r sw i th mo r eth an2 5 0p ub l i c a t ion sa c co un tfo r2 2 . 5%o fth eo v e r a l l c i t a t ionin e q u a l i t y .A f t e rth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r e ,wh e r ec l u s t e rm e anc i t a t ion sa r e u s e da sno rm a l i z a t ionf a c to r s ,th i sf i g u r ei sr e d u c e dto4 . 3% .S e cond l y ,th ed i f f e r en c e sb e tw e enth e T a r g e t(o rc i t eds id e ) no rm a l i z a t ion p ro c ed u r e sd ep end onag i v enc l a s s i f i c a t ions y s t emin c l ud in ga n umb e ro f h e t e ro g en eo u sf i e ld s .Tor e co gn i z eth i sf e a t u r e ,i ti su s e f u ltor e f e rtoth e s ep ro c ed u r e sa sf i e ld no rm a l i z edno rm a l i z a t ion p ro c ed u r e s .Th i s i sth ep r a c t i c ew efo l low inth i sp ap e r . 4 5 un i v e r s i t yr an k in g sob t a in e dw i thth etwo m e thod sfo rso l v in gth ea l l s c i en c e sa g g r e g a t ionp rob l emi s o fav e r ysm a l lo rd e ro fm a gn i t ud efo rbo thc i t a t ion imp a c t ind i c a to r s . Th er e s to fth ep ap e ri so r g an i z e din tofo u rs e c t ion s .S e c t ionI Iin t rod u c e sth ec i t a t ionimp a c t ind i c a to r s ,andi t sp rop e r t i e s .S e c t ionI I Ip r e s en t sth etwoso l u t ion stoth ea l l s c i en c e sa g g r e g a t ion p rob l em .S e c t ionIVd e s c r ib e sth ed a t a ,and in c l ud e sth eemp i r i c a lr e s u l t s ,wh i l eS e c t ionVcon c l ud e s . I I .C ITAT IONIMPACTIND ICATORS I I . 1 . No t a t ion I ti snowcon v en i en ttoin t rod u c esom eno t a t ion s .G i v enas e tD o fN d i s t in c ta r t i c l e s ,andJ s c i en t i f i cf i e ld sind e x e db yj=1 ,… ,J ,ac l a s s i f i c a t i o ns y s t emi sana s s i gnm en to fa r t i c l e sinD toth eJ f i e ld s .L e tIb eth en umb e ro fr e s e a r chun i t s ,ind e x e db yi=1 ,… ,I .Fo rs imp l i c i t y ,inth i sS e c t ionw e a s s um eth a tth e r ei snoco a u tho r sh ip ,soth a te a cha r t i c l einD b e lon g stoas in g l eun i tinI . L e tc e i jkb th en umb e ro fc i t a t ion sr e c e i v e db yth ektha r t i c l eo fun i tiinf i e ldj .Th enc c }d eno t e sth e i j={ i jk c i t a t i o nd i s t r i b u t i o no fu n i t i i n f i e l d j , wh i l ec eno t e sth ec i t a t i o nd i s t r i b u t i o no f f i e l dj ,th a t i s ,th eun iono fa l l jd r e s e a r chun i t s ’c i t a t iond i s t r ib u t ion sinth a tf i e ld :c c } .Und e rth es imp l i f y in ga s s ump t iono f j=∪i{ i j 5 nocoa u tho r sh ip ,th es e to fd i s t r ib u t ion sc o rmap a r t i t iono fc . F in a l l y ,l e tC=∪j{ c }=∪i∪j i jf j j { c }b eth eo v e r a l lc i t a t i o nd i s t r i b u t i o n ,o rth ec i t a t iond i s t r ib u t ioninth ea l l s c i en c e sc a s e .Fo rl a t e r i j r e f e r en c e ,l e tNi eth en umb e ro fa r t i c l e sind i s t r ib u t ionc ,l e tNi=Σj N eth eto t a ln umb e ro f jb i j i jb a r t i c l e sp ub l i sh e db yun i ti , andl e tNj=Σi N eth eto t a ln umb e ro fa r t i c l e sinf i e ldj .O fco u r s e , th e i jb . to t a ln umb e ro fa r t i c l e s inth ea l l s c i en c e sc a s e i sN =ΣiΣjNi j Ino u rcon t e x t , wh e r eine v e r yf i e ldjw eh a v ec c } ,th ee v a l u a t iono fan yc i t a t ion j= ∪i{ i j d i s t r ib u t ioni sdon et a k in gin toa c co un tak e ych a r a c t e r i s t i co fd i s t r ib u t ionc ,s a yθj.Th u s ,ac i t a t i o n j 5M o r eg en e r a l l y , inth i sS e c t ionw ea s s um eth a tth ea s s i gnm en to fa r t i c l e sinD toth eIr e s e a r chun i t si ss u chth a tth es e t o fd i s t r ib u t ion sc o rmap a r t i t iono fc . i jf j 6 im p a c ti n d i c a t o ri saf un c t ionF d e f in e dinth ep rod u c tsp a c eo fa l lc i t a t iond i s t r ib u t ion sandth e ch a r a c t e r i s t i csp a c e ,soth a t– g i v enθj–th ee xp r e s s ionFi ( c ;θj)d eno t e sth ec i t a t ionimp a c to f j=F i j un i tiinf i e ldj ,wh i l eFj=F( c ;θj)d eno t e sth ec i t a t ionimp a c to ff i e ldja sawho l e .Toc l a r i f yth i s j no t ion ,con s id e rth efo l low in gth r e e ind i c a to r sth a tw i l lb eu s e d inth i sp ap e r . 1 .L e tµi ndµj b eth em e anc i t a t iono fd i s t r ib u t ion sc ndc ,r e sp e c t i v e l y .Th eR e l a t i v em e a n ja i ja j c i t a t i o n i n d i c a t o r ,M , i sd e f in e da s Mi c ; µj)=µi /µj . j=M( i j j ( 1 ) Inth i sc a s e ,θj=µj .Fo rf i e ld ja sawho l e ,Mj=µj /µj =1 . 2 .L e tXjb eth es e to fth e1 0% mo s tc i t e da r t i c l e sinc i t a t iond i s t r ib u t ionc ,andl e tXi eth e j jb s ub s e to fa r t i c l e sinXjco r r e spond in gtoun i ti ,soth a t Xj=∪i{ Xij} w i thXijnonemp t yfo rsom ei . I fn sth en umb e ro fa r t i c l e s inXij,th enth e T o p1 0% i n d i c a t o r ,T ,i sd e f in e da s i ji Ti ( c ; Xj)=n /Ni . j =T i j i j j ( 2 ) Inth i sc a s e ,θj=Xj .I fn sth en umb e ro fa r t i c l e sinXj ,th enfo rf i e ldja sawho l e ,Tj=T( c ; j=Σ in i ji j Xj)=n /Nj =0 . 1 0 . j 3 .L e tz eth eC r i t i c a lC i t a t i o nL i n e– CCLh e r e a f t e r–fo rc i t a t iond i s t r ib u t ionc ,andd eno t eth e jb j a r t i c l e sinc i thc i t a t ion se q u a ltoo rg r e a t e rth anz sh i g h im p a c ta r t i c l e s .Fo ran yh i ghimp a c ta r t i c l e jw ja w i thc i t a t ion sc ,th e CCLn o rm a l i z e dh i g h im p a c tg a pi sd e f in e da s( c ) / z .Con s id e rth ef am i l yo fFGT i l i l-z j j ind i c a to r sin t rod u c e din A lb a r r áne ta l .( 2 0 1 1 a )a sf un c t ion so fno rm a l i z e dh i gh imp a c tg ap s . Th e s e condm emb e ro fth i sf am i l y ,r e f e r r e dtoa sth eA v e r a g eo fh i g h im p a c tg a p s, A ,i sd e f in e da s c ; z )=( 1 /Ni ) [ Σl( c z ) / z ] , Ai j=A( i j j j i lj j 7 ( 3 ) wh e r eth es um i so v e rth eh i gh imp a c ta r t i c l e s inc h a tb e lon gtoc i t a t iond i s t r ib u t ionc .Inth i sc a s e , jt i j θj=z .Fo rth een t i r ef i e ld ja sawho l e ,w eh a v eAj=A( c ; z )=( 1 /Nj ) [ Σk( c z ) / z ] ,wh e r eth es um j j j kj j i so v e rth eh i gh imp a c ta r t i c l e s in c . j Tof a c i l i t a t eth ecomp a r i son w i th Ti ,inth es e q u e lw ew i l la lw a y sf i xz sth en umb e ro f j ja th c i t a t ion so fth ea r t i c l einth e9 0 p e r c en t i l eo fc i t a t iond i s t r ib u t ionc .Inth a tc a s e ,th es e to fh i gh j imp a c ta r t i c l e sco in c id e sw i thth es e to fth e1 0% mo s tc i t e da r t i c l e s inc i t a t iond i s t r ib u t ionc .Ino th e r j wo rd s ,fo rbo thind i c a to r sw eh a v e θj= z . Th etwo m a ind i f f e r en c e sb e tw e enT andA a r eth e j fo l low in g .F i r s t l y ,on eo r mo r ec i t a t ion sr e c e i v e db yah i gh imp a c ta r t i c l ein c r e a s e sAi u tdo e sno t jb ch an g eTi .Ino th e r wo rd s ,A i s mono ton i cb u tTi sno t .S e cond l y ,Ti s mo r erob u s ttoe x t r em e j ob s e r v a t ion sth anA. I I . 2 .S i z e-ands c a l e ind ep end en c e Con s id e rth efo l low in gtwod i f f i c u l t i e sfo rcomp a r in gth ec i t a t ion imp a c to fan yp a iro fr e s e a r ch un i t s :th etwoun i t sm a yb eo fd i f f e r en ts i z e s ,andi fth e y wo r kind i f f e r en tf i e ld s ,th enth e i rr aw c i t a t ion sa r eno td i r e c t l ycomp a r ab l e .Tos e ehowtoo v e r com eth ef i r s td i f f i c u l t y ,a s s um eth a tw eh a v e twoc i t a t iond i s t r ib u t ion sc ndc o run i t su andvinf i e ldj .Inth ee x amp l eg i v eninth e u j a v jf r In t rod u c t ion ,ui sH a r v a rd ,vi sJohn Hop k in s ,andj i sE conom i c s .G i v enan yd i s t r ib u t ionc ,l e tc b e n ind i c a to rFi ss a idtob es i z e i n d e p e n d e n ti f ,fo ran yc i t a t iond i s t r ib u t ion th er thr ep l i c ao f i t .G i v enθ,a r r t c , F( c ; θ)=F( c ; θ)fo ra l lr .N e x t , l e t c eth er r ep l i c ao fd i s t r ib u t ionc i thr=Nv ,and l e t c e u j w j u jb v jb r t th et r ep l i c ao fd i s t r ib u t ionc i tht=Nu . Now c ndc a v eth es am es i z ee q u a ltoNv im e sNu . v j w j jt j u ja v jh r t Th u s ,i f Fi ss i z e ind ep end en t ,soth a tF( c ) =F( c )andF( c ;θj) =F( c ;θj) ,th ef i r s t j u j;θ j v j u j;θ v j d i f f i c u l t y i so v e r com e . 8 Tos e ehowtoh and l eth es e condd i f f i c u l t y ,l e tc ndc etwoc i t a t iond i s t r ib u t ion sfo run i ti i ja lwb inf i e ld j ,andfo run i t vinf i e ldw.Inth ee x amp l em en t ion e d inth eIn t rod u c t ion , i= M IT ,j= O r g an i c Ch em i s t r y ,v= O x fo rdUn i v e r s i t y ,andw =S t a t i s t i c sandP rob ab i l i t y .A nind i c a to r Fi ss a idtob es c a l e i n d e p e n d e n ti f ,fo ran yc i t a t iond i s t r ib u t ionc ,an ych a r a c t e r i s t i cθ,andan yλ>0 ,F( λc ;λθ)=F( c ;θ) . N e x t ,l e t b=θj/θw,andcon s id e rth eno rm a l i z e dd i s t r ib u t ionc ’ c ’ } ,wh e r ec ’ /bfo ra l lk i j={ i jk i jk=c i jk =1 , . . ,Ni . No t eth a tθ’ /b=θw,soth a tc i t a t iond i s t r ib u t ion sc ’ ndc r enowcomp a r ab l e j j=θ j i ja lw a und e rθw. Th u s ,i fFi ss c a l e ind ep end en t ,soth a tF( c ;θj) =F( c ’ ;θ’ ) =F( c ’ ;θw) ,th es e cond i j i j j i j d i f f i c u l t y i so v e r com e . Anind i c a to r Fi ss a idtob ea dm i s s i b l ei fi ti ss i z e -ands c a l e ind ep end en t .T h eh ind e xi san impo r t an te x amp l eo fanind i c a to rth a ti sn e i th e rs i z e -no rs c a l e ind ep end en t . Onth econ t r a r y ,t h e th r e eind i c a to r sd e f in e d ine xp r e s s ion s( 1 ) ,( 2 ) ,and( 3 )a r egoode x amp l e so fadm i s s ib l e ind i c a to r s . I I . 3 .Th eadd i t i v ed e compo s ab i l i t yp rop e r t y Th efo l low in gp rop e r t yi sv e r ycon v en i en t .G i v en θ,a nind ic a to rFi ss a idtob ea d d i t i v e l y d e c om p o s a b l ei ffo ran yp a r t i t iono fac i t a t iond i s t r ib u t ioncin toG d i s jo in ts ub g ro up s ,ind e x e db yg= 1 , . . . ,G,th ec i t a t ion imp a c to fd i s t r ib u t ion cc anb ee xp r e s s e da sfo l low s : F( c ; θ)=Σg( n /n ) F( c ; θ) , g g sth en umb e ro fp ub l i c a t ion sins ub g ro upg ,andn=Σgn sth en umb e ro fp ub l i c a t ion sin wh e r en gi gi d i s t r ib u t ionc .Toi l l u s t r a t eth eu s e f u ln e s so fth i sp rop e r t y ,con s id e rth efo l low in gth r e es i t u a t ion sin wh i chth e ind i c a to rFi sa s s um e dtob eadm i s s ib l e . c } ,andth ed i s t r ib u t ion sc ,i= A.Und e ro u ra s s ump t ion s ,ine v e r yf i e ld jw eh a v ec j=∪i{ i j i j 1 ,… ,I ,con s t i t u t eap a r t i t iono f c .I f Fi sadd i t i v e l yd e compo s ab l e ,th enw ec anw r i t e j F( c ; θj ) ,=Σi( Ni /Nj ) F( c ; θj ) . j j i j 9 ( 4 ) Th i si sav e r yn a t u r a lcond i t ion ,ind i c a t in gth a tth ec i t a t ionimp a c to ff i e ld ja sa who l ec anb e e xp r e s s e da sth ew e i gh t e da v e r a g eo fth er e s e a r chun i t s ’c i t a t ion imp a c tund e racommonθj . B.A s s um eth a tco un t r yvcon s i s t so fRr e g ion s ,ind e x e db yr=1 ,… ,R,anda s s um eth a tth eR c i t a t iond i s t r ib u t ion sinf i e ldj ,c ,fo rmap a r t i t iono fth ec i t a t iond i s t r ib u t iono fco un t r yvinth a t v r j f i e ld ,c .I f Fi sadd i t i v e l yd e compo s ab l e ,th enw ec anw r i t e v j F( c ; θj )=Σr( Nvr /Nv) F( c ; θj ) , v j j v r j ( 5 ) wh e r eNvr sth en umb e ro fp ub l i c a t ion sinr e g ionr ,soth a tNv .E q u a t ion( 5 )ind i c a t e sth a t ji j=Σ rNi r j th ec i t a t ionimp a c to fco un t r yvinf i e ldjc anb ee xp r e s s e da sth ew e i gh t e da v e r a g eo fth er e g ion s ’ c i t a t ion imp a c t inf i e ldjund e racommonθj . C. A s s um eth a tc anb ep a r t i t ion e din toSh e t e ro g en eo u ss ub f i e ld s ,ind e x e db ys=1 ,… ,S,so jc th a tc c } ,wh e r ec sth ec i t a t iond i s t r ib u t iono fs ub f i e ldsinf i e ldj .I fFi sadd i t i v e l y j= ∪s{ s j s ji d e compo s ab l e ,th enw ec anw r i t e F( c ; θj )=Σs( Ns /Nj ) F( c ; θj ) , j j s j ( 6 ) wh e r eNs sth en umb e ro fp ub l i c a t ion sins ub f i e lds ,soth a tNj=ΣsNs .E q u a t ion( 6 )ind i c a t e sth a t ji j th ec i t a t ionimp a c tinf i e ldja sa who l ec anb ee xp r e s s e da sth ew e i gh t e da v e r a g eo fth es ub f i e ld c i t a t ionimp a c tv a l u e s .How e v e r ,th i se xp r e s s ionadd sc i t a t ionimp a c tv a l u e sco r r e spond in gtor aw tth ef i e ld c i t a t iond i s t r ib u t ion so fh e t e ro g en eo u ss ub f i e ld su s in ga sr e f e r en c eth ech a r a c t e r i s t i cθja l e v e l .Th u s ,a l tho u ghth i sd e compo s i t ioni sm a th em a t i c a l l ypo s s ib l e ,i tdo e sno tp ro v id eas a t i s f a c to r y so l u t iontoth ea g g r e g a t ionp rob l em m en t ion e dinno t e1 .S u chaso l u t ionw i l lh a v etow a i tun t i lth e n e x tS e c t ion . F in a l l y ,no t eth efo l low in gtwopo in t s .F i r s t l y ,e q u a t ion( 4 )c anb ew r i t t ena sfo l low s : Σi( Ni /Nj )[ F( c , θj ) / F( c ; θj ) ]=1 , j i j j 10 soth a tth ev a l u eon ec ans e r v ea sab en chm a r kfo re v a l u a t in gth er e s e a r chun i t sinth eu s u a lw a y .Th e s am ec anb es a ido fe q u a t ion s( 5 )and( 6 ) .S e cond l y ,th eth r e eadm i s s ib l eind i c a to r sin t rod u c e din e xp r e s s ion s( 1 ) ,( 2 ) ,and( 3 )a r eadd i t i v e l yd e compo s ab l e . I I I .THESOLUT IONSTOTHEALL -SC IENCESAGGREGAT IONPROBLEM I I I . 1 .Th e so lu t iontoth ea l l s c i en c e sagg r eg a t ionp rob l emu s ingth est and a rdf i e ld no rm a l i z a t ionp ro c edu r e D i f f e r en c e sinp rod u c t ionandc i t a t ionp r a c t i c e sa c ro s sf i e ld sm a k e si timpo s s ib l e tod i r e c t l y a g g r e g a t eth er awc i t a t ion sr e c e i v e db ya r t i c l e sind i f f e r en tf i e ld s .Ino rd e rtoso l v eth ea l l s c i en c e s a g g r e g a t ion p rob l em , on e po s s ib i l i t yi sto u s ea no rm a l i z a t ion p ro c e d u r e .A sind i c a t e dinth e In t rod u c t ion ,g i v eni t ss imp l i c i t yandgoodp e r fo rm an c e ,inth i sp ap e rw eadop tth es t and a rdf i e ld no rm a l i z a t ionp ro c e d u r einwh i chth er awc i t a t ions co r e sinan yf i e lda r eno rm a l i z e du s in gth ef i e ld m e anc i t a t iona sth eno rm a l i z a t ionf a c to r . Fo rm a l l y ,fo ran ya r t i c l ekinc i t a t iond i s t r ib u t ionc ,th eno rm a l i z e dn umb e ro fc i t a t ion sc * s i j i jki d e f in e da s c * µj . i j k=c i j k/ Th en o rm a l i z e do v e r a l lc i t a t i o nd i s t r i b u t i o ni sC* =∪i{ c* } ,wh e r ec* c * }i sth en o rm a l i z e d i i=∪j∪k { i jk c i t a t i o nd i s t r i b u t i o no fu n i tii nt h ea l l s c i e n c e sc a s e .S in c eno rm a l i z e dc i t a t ion sa r enowcomp a r ab l e ,i tm a k e s . G i v enth ek e ych a r a c t e r i s t i c θ*o fd i s t r ib u t ion s en s etoapp l yan yind i c a to rtoc i t a t iond i s t r ib u t ionc* i C*,f o ran yi ,l e tF *i=F( c* ;θ* )b eth ec i t a t ionimp a c to fd i s t r ib u t ionc* c co rd in gtoth eind i c a to r i ia *va r enowcomp a r ab l e , F.Fo ran yp a i ro fr e s e a r chun i t suandv ,th ec i t a t ionimp a c tv a l u e sF *uandF 6 andc anb eu s e dtor an kth etwoun i t s inq u e s t ion . S in c eFi sa s s um e dtob eadd i t i v e l yd e compo s ab l e , w ec anw r i t e 6T h ea g g r e g a t iono fSh e t e ro g en eo u ss ubf i e ld se x am in edins i t u a t ion CinS ub s e c t ionI I . 3 ,adm i t sas im i l a rso l u t ion : ; θ* )=Σs( Nsj/Nj) F( c* ; θ* ) . F( c* j s j 11 F *=F( C*;θ* )=Σi( Ni/N) F *i. Th u s,i fw er an kun i v e r s i t i e sb yth er a t ioF *i/F *,i =1 ,… ,I ,th enth ev a l u eon ec ans e r v ea sa b en chm a r kfo re v a l u a t in gth er e s e a r chun i t s inth eu s u a lw a y . Fo r l a t e rr e f e r en c e ,s in c ec* c* } , fo re a chiw ec anw r i t e : i=∪j{ i j F *i = F( c* ; θ* )=Σj( Nij/Ni)F ( c* ; θ* )=χi(c* , j=1 ,… ,J , θ* ) . i i j i j ( 7 ) No t eth a t ,fo re a ch i , F *id ep end son l yonc* , j=1 ,… ,J , andth ecommony a rd s t i c kθ* ,th a t i s , F *i= i j χi(c* , j=1 ,… ,J , θ* ) . i j I I I . 2 .Aso lu t iontoth ea l l s c i en c e sagg r eg a t ionp rob l emw i thou tf i e ld -no rm a l i z a t ion Fo ran yun i ti inan yf i e ldj ,g i v enθjth ee xp r e s s ionFij=F( c ;θj)i sth ec i t a t ionimp a c to fi inj i j a c co rd in gtoind i c a to rF.Acon v en i en tm e a s u r eo fc i t a t ionimp a c tfo run i tiinth ea l l s c i en c e sc a s e , Φi,c anb ed e f in eda sth ew e i gh t e da v e r a g eo fth ev a l u e sFija ch i e v e dina l lf i e ld s ,w i thw e i gh t se q u a l toth er e l a t i v e impo r t an c eo fe a chf i e ldinth eto t a lp rod u c t iono fun i ti . Add in gup“ adm i s s ib l e ”F( c ; s j θj )v a l u e sfo rd i f f e r en tf i e ld sund e rch a r a c t e r i s t i cθjine a cho fth emsho u ldpo s enop rob l ema ta l l . No t eth a tth i sm e a s u r e , Fi,i saf un c t ionϕi o fe v e r yc i t a t iond i s t r ib u t ionc nde v e r yθjfo ra l lj= i ja 1 ,… ,J : 7 Φi=ϕi( c , θj, j=1 ,… ,J )=Σj( Nij/Ni) Fij. i j ( 8 ) c* } ,wh e r ec* A f t e rth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r e ,w eh a v eC* =∪j{ j j=∪i∪k { c * }i sth en o rm a l i z e dc i t a t i o nd i s t r i b u t i o no ff i e l dj .L e tθ* eth ech a r a c t e r i s t i co fc* n a lo go u stoth e i jk jb ja c h a r a c t e r i s t i cθ*o fC*,soth a tθ*= Σj( Nj/N) θ* ,andθ* /µj .Th e r e fo r e ,s in c eFi ss c a l e j j= θ j ind ep end en t , Fij=F( c ; θj)=F( c* ; θ* )fo ra l lj .H en c e ,e q u a t ion( 8 )c ann ew r i t t ena sfo l low s : i j i j j 7T h ea g g r e g a t iono fSh e t e ro g en eo u ss ubf i e ld se x am in ed ins i t u a t ionC inS ub s e c t ionI I . 3 ,adm i t sas im i l a rso l u t ion :F( c ; j θj)=Σs( Nsj/Nj) F( c ; θsj) ,wh e r eθsji sth ech a r a c t e r i s t i co fc i t a t iond i s t r ib u t ionc tth es ub f i e ld l e v e lfo re v e r yj =1 ,… ,J . s j s ja 12 Φi=ϕ( c , θj, j=1 ,… ,J )=Σj( Nij/Ni)F ( c* ; θ* ) . i j i j j ( 9 ) Th ecomp a r i sono fe xp r e s s ion s( 7 )and( 9)i l l u s t r a t eth ed i f f e r en c e sb e tw e enth etwoso l u t ion stoth e a l l s c i en c e sa g g r e g a t ionp rob l em wh enth ee v a l u a t iono fth eun i t s ’c i t a t ionimp a c ti sm ad ew i th add i t i v e l yd e compo s ab l eind i c a to r s .Fo ran yi ,F( c* ;θ* )ine q u a t ion( 7 )m e a s u r e sth ec i t a t ionimp a c t i j o fun i ti inf i e ldju s in ga sr e f e r en c eth ech a r a c t e r i s t i cθ*o fth eo v e r a l lno rm a l i z e dc i t a t iond i s t r ib u t ion C*. How e v e r ,F( c* ;θ* )=F( c ;θj)ine q u a t ion( 9 )m e a s u r e sth ec i t a t ionimp a c to fun i tiinf i e ldj i j j i j u s in ga sr e f e r en c eth ech a r a c t e r i s t i cθ* fe a chc i t a t iond i s t r ib u t ionc* r ,wh a ti sth es am e ,u s in ga s jo jo r e f e r en c eth ech a r a c t e r i s t i cθjo fe a chc i t a t iond i s t r ib u t ionc r io rtoapp l y in gth es t and a rdf i e ld jp no rm a l i z a t ionp ro c e d u r e . Con s e q u en t l y ,comp u t in gΦi= ϕ( c ,θj,j=1 ,… ,J )a vo id sth epo s s ib l e i j e r ro r scomm i t t e d inth eno rm a l i z a t iono fr awc i t a t ions co r e su s in gth ep ro c e d u r e in( 7 ) . I t i scon v en i en ttocomp u t eth ew e i gh t e da v e r a g eo fth eFiv a l u e sa sfo l low s : Φ=Σi( Ni/N)Φi=Σi( Ni/N)Σj( Nij/Ni) Fij=ΣiΣj( Nij/N) Fij. ( 1 0 ) Th u s,a sb e fo r e , i fw er an kun i v e r s i t i e sb yth er a t io Fi/F, i=1 ,… ,I , th enth ev a l u eon ec ans e r v ea sa b en chm a r kfo re v a l u a t in gth er e s e a r chun i t s inth eu s u a lw a y. Inp r a c t i c e ,w eh a v ein fo rm a t ioncon c e rn in gsom e– th e5 0 0 LRun i v e r s i t i e s–b u tno ta l l r e s e a r chun i t s .Th e r e fo r e ,w ec anno tcomp u t eΦ u s in ge xp r e s s ion( 1 0 ) .S t a r t in gf romth a te xp r e s s ion , w eh a v e Φ=ΣiΣj( Nij/N) Fij=Σj( Nj/N)Σi( Nij/Nj) Fij. S in c ec c } ,andFi sadd i t i v e l yd e compo s ab l e ,Σi( Nij/Nj) Fij=Fj,wh e r eFj=F( c ,θj)c anb e j j=∪i{ i j comp u t e dw i tho u rd a t a .Th e r e fo r e ,w ec ancomp u t eΦ a sfo l low s Φ=Σj( Nj/N)Fj. 13 Onth eo th e rh and ,s in c e Fj=F (c ,θj)=F *j=F (c* ,θ* ) ,w eh a v eF *=Φ.F in a l l y ,no t eth a twh enF j j j =M, F *=Φ =1 ,wh i l ewh enF=T, F *=Φ =0 . 1 0 . I I I . 3 .Th ea imo fth ep ap e r Th em a ina imo fth i sp ap e ri sth ecomp a r i sonb e tw e enth er an k in g so fr e s e a r chun i t sob t a in e d w i thand w i tho u tth es t and a rdf i e ld -no rm a l i z a t ion p ro c e d u r e ,(F *1, … ,F *I)and( Φ1, … ,ΦI) , r e sp e c t i v e l y .Tound e r s t andth ew a yth er e s u l t sw i l lb ep r e s en t e d ,r e c a l lth a t ,fo ran yj ,Xji sth es e to f h i gh imp a c ta r t i c l e sind i s t r ib u t ionc ,th a ti s ,th es e to fa r t i c l e sinc i thc i t a t ion se q u a ltoo rg r e a t e r j jw th anz ,o rth es e to fth e1 0% mo s tc i t e da r t i c l e si nc .L e tu sd eno t eb y X=(X1,… , Xj ,… , XJ)th es e t j j o fh i gh imp a c ta r t i c l e sinth ea l l s c i en c e sc a s e . Onth eo th e rh and ,l e tY b eth es e to fth e1 0% mo s t c i t e da r t i c l e s inth eo v e r a l lno rm a l i z e dc i t a t iond i s t r ib u t ionC*=∪j{ c* } ,and l e t Yjb eth es ubs e to f j a r t i c l e s inY b e lon g in gtof i e ldj ,soth a t Y=(Y1,… , Yj ,… , YJ) . Und e rth eun i v e r s a l i t ycond i t ion ,th a ti s ,i fa l lf i e ld sa r ee q u a l l yd i s t r ib u t e de x c ep tfo ras c a l e f a c to r ,th enth eno rm a l i z a t ionp ro c e d u r ew i l le l im in a t ea l ld i f f e r en c e sb e tw e enc i t a t ionp r a c t i c e s a c ro s sc l u s t e r s ,andth etwoso l u t ion stoth ea l l s c i en c e sa g g r e g a t ionp rob l emw i l lco in c id e . Th er e a son i sth a t inth i ss i t u a t ionw ewo u ldh a v e z * /µj=z *fo ra l lj .Con s e q u en t l y , Yj=Xjfo ra l lj ,and Y= j=z j X.S in c ec i t a t iond i s t r ib u t ion sc* ndc a v eth es am en umb e ro fa r t i c l e sando u rind i c a to r sa r ea i ja i jh c ;z )=F( c* ;z * )=F( c* ;z * )=F *ij f un c t ionso l e l yo fh i gh imp a c ta r t i c l e s ,w ewo u ldh a v eFij=F( i j j i j j i j fo ra l liandj .Inv i ewo fe q u a t ion s( 7 )and( 8 ) ,w ewo u ldh a v eF *i=Φifo ra l li .Ino th e rwo rd s ,th e r an k in g s( F *1, … , F *I)and( Φ1, … , ΦI)w i l lb e id en t i c a l . A sw eknow ,inp r a c t i c eth eun i v e r s a l i t ycond i t ioni sno ts a t i s f i e d(A lb a r r án e ta l . ,2 0 1 1b , W a l tm an e ta l . ,2 0 1 2b ,Th e lw a l l& W i l son ,2 0 1 4 , and B r z e z in s k i, 2 0 1 5 ) .Con s e q u en t l y ,th e p e r fo rm an c eo fth ef i e ld -no rm a l i z a t ionp ro c e d u r ec anno tb ep e r f e c t ,andth es e t sY andX w i l lno t 14 co in c id e .Inth i ss i t u a t ion ,w esho u ld m e a s u r eth econ s e q u en c e so fadop t in gth etwoso l u t ion stoth e a l l s c i en c e sa g g r e g a t ionp rob l emu s in gind i c a to r sw i thd i f f e r en tp rop e r t i e s .Th er e a son ,o fco u r s e ,i s th a twh en e v e rY andX d i f f e r ,th a ti s ,wh enth es e to fh i gh imp a c ta r t i c l e sund e rth etwoso l u t ion s d i f f e r ,th econ s e q u en c e sfo rth eun i v e r s i t yr an k in g sm i gh tb eo fad i f f e r en to rd e ro fm a gn i t ud e d ep end in gonth ec i t a t ion imp a c t ind i c a to rw eu s e . F in a l l y ,no t eth a t ,g en e r a l l y ,F *i≠Fi fo ra l li=1 ,… ,I . How e v e r , i t i se a s ytoe s t ab l i shth a tth i s i sno tth ec a s efo rth er e l a t i v em e an ind i c a to r M.A sam a t t e ro ff a c t , M *i=( 1 / Ni)ΣjΣkc * ( 1/ Ni)ΣjΣkc µj i j k = i j k/ i ss imp l yth eM e anNo rm a l i z e dC i t a t ionS co r e ind i c a to r .How e v e r , Mi=Σj( Nij/ Ni)Mij=Σj( Nij/Ni)( µi /µj )=( 1/ Ni)ΣjΣkc µj=M *i . j i j k/ Th e r e fo r e ,inth eemp i r i c a lp a r to fth ep ap e rw ew i l lon l ys t ud yth eun i v e r s i t yr an k in g sob t a in e dw i th th e ind i c a to r sTandA,n am e l y ,th etop1 0%andth ea v e r a g eo fh i gh imp a c tg ap s . IV .EMP IR ICALRESULTS IV . 1 .Th ed a t aandd e s c r ip t i v es t a t i s t i c s O u rd a t a s e tr e s u l t sf romth eapp l i c a t ion o fa p ub l i c a t ion l e v e la l go r i thm i cm e thodo lo g y to 9 , 4 4 6 , 6 2 2d i s t in c ta r t i c l e sp ub l i sh e din2 0 0 3 2 0 1 2( s e eR u i z -C a s t i l lo & W a l tm an ,2 0 1 5 ) .P ub l i c a t ion sin lo c a ljo u rn a l s ,a sw e l la spop u l a rm a g a z in e sandt r ad ejo u rn a l s ,h a v eb e ene x c l ud e d( s e eR u i z -C a s t i l lo& W a l tm an ,2 0 1 5 ,fo rth ed e t a i l s ) .W ewo r kw i thjo u rn a l sinth es c i en c e s ,th eso c i a ls c i en c e s ,andth ea r t s andh um an i t i e s ,a l tho u gh m an ya r t sandh um an i t i e sjo u rn a l sa r ee x c l ud e db e c a u s eth e ya r eo falo c a l n a t u r e . Th ec l a s s i f i c a t ions y s t emcon s i s t so f5 , 1 1 9c l u s t e r s ,andc i t a t iond i s t r ib u t ion sr e f e rtoth e c i t a t ion sr e c e i v e db yth e s ea r t i c l e sd u r in gaf i v e y e a rc i t a t ionw indowfo re a chy e a r inth a tp e r iod . Inth i s p ap e r ,w efo c u sonth es e to f3 , 6 1 4 , 4 4 7d i s t in c ta r t i c l e sp ub l i sh e dinth ep e r iod2 0 0 5 2 0 0 8 .Int e rm so f 15 th eno t a t ionin t rod u c e dinS e c t ionI I . 1 ,w eh a v eC = ∪j{ c }=(c ,… ,c i thJ= 5 , 1 1 9 ,andN = j 1 N) w 3 , 6 1 4 , 4 4 7 . Weso r tc l u s t e r sin d e c r e a s in go rd e rb ys i z e , wh e r es i z ei sm e a s u r e da sth en umb e ro f p ub l i c a t ion s ,andg ro upc l u s t e r sin tot end e c i l ec l a s s e s ,ind e x e db yd =1 ,… ,1 0 . .Fo re a chd e c i l e ,th e a v e r a g en umb e ro fp ub l i c a t ion sp e rc l u s t e r ,d eno t e db ymd,andth ea v e r a g en umb e ro fc i t a t ion sp e r p ub l i c a t ion ,d eno t e db yµd,a r einT ab l e1 . No t eth ep r e s en c eo fal a r g en umb e ro fsm a l lc l u s t e r sw i th l e s sth ano re q u a lto1 0 0p ub l i c a t ion s( t yp i c a l l ya c comp an i e db yalow m e anc i t a t ionp e ra r t i c l e ) . How e v e r ,th es e to fsm a l lc l u s t e r sin c l ud e sav e r ysm a l lp ropo r t iono fth e3 . 6m i l l iona r t i c l e sinth e en t i r ed a t a s e t( s e erowD inT ab l e1 ) . T ab l e1a roundh e r e Th er es e a r chun i t sa r eun i v e r s i t i e s .A sin W a l tm ane ta l .( 2 0 1 2b ) ,p ub l i c a t ion sa r ea s s i gn e dto un i v e r s i t i e su s in gth ef r a c t ion a lco un t in gm e thodth a tt a k e s in toa c co un tth eadd r e s s l in e sapp e a r in g in e a chp ub l i c a t ion .W ea r eon l ycon c e rn e dw i thth e2 , 4 2 0 , 0 5 4d i s t in c ta r t i c l e s ,o r6 7%o fth eto t a l ,w i th a tl e a s ton eadd r e s sl in eb e lon g in gtoanLRun i v e r s i t y .Anya r t i c l eo fth i st yp ei sf u l l ya s s i gn e dtoan LRun i v e r s i t yon l y i fa l ladd r e s s e sm en t ion e d inth ep ub l i c a t ionb e lon gtoth eun i v e r s i t y inq u e s t ion .I f ap ub l i c a t ioni sco a u tho r e db ytwoo r mo r eLRun i v e r s i t i e s ,th eni ti sa s s i gn e df r a c t ion a l l ytoa l lo f th eminp ropo r t iontoth en umb e ro fadd r e s sl in e sine a chc a s e .Fo re x amp l e ,i fth eadd r e s sl i s to fan a r t i c l econ t a in sf i v eadd r e s s e sandtwoo fth emb e lon gtoap a r t i c u l a run i v e r s i t y ,th en0 . 4o fth ea r t i c l e i sa s s i gn e dtoth i sun i v e r s i t y ,andon l y0 . 2o fth ea r t i c l ei sa s s i gn e dtoe a cho fth eo th e rth r e e un i v e r s i t i e s .F in a l l y ,con s id e rap ub l i c a t ionco a u tho r e db yanLRun i v e r s i t yandanun knownn umb e r o fo th e rin s t i t u t ion so u t s id eth eL e id enR an k in g .A s s um e ,fo re x amp l e ,th a tth ep ub l i c a t ionh a sfou r add r e s s l in e s ,twoo fwh i chco r r e spondtoth eLRun i v e r s i t y .Inth i sc a s e ,on l y0 . 5o fth ea r t i c l ew i l lb e a s s i gn e dtoth eLRun i v e r s i t y . Th i sp ro c e d u r eimp l i e sth a tth eto t a lf r a c t ion a ln umb e ro fa r t i c l e s a s s i gn e dtoLRun i v e r s i t i e sw i l lb esm a l l e rth anth eto t a ln umb e ro fa r t i c l e sw i tha tl e a s ton eadd r e s s 16 l in eb e lon g in gtoanLRun i v e r s i t y .I tt u rn so u tth a tth i sn umb e ri s1 , 8 8 6 , 1 0 6 . 1 ,o r5 2 . 2%o fth eto t a l . Th ed i s t r ib u t iono fth i sto t a lamon gth e5 0 0un i v e r s i t i e si sinco l umn s1and2inT ab l e Ainth e App end i x . F in a l l y ,w ecomp a r eth es k ewn e s sandc i t a t ionin e q u a l i t yo fth eth r e ed i s t r ib u t ion scon s i s t in go f 3 . 6 ,2 . 4 ,and1 . 9m i l l iona r t i c l e su s in gth eCh a r a c t e r i s t i cS co r e sandS c a l e sapp ro a ch( S ch ub e r te ta l . , 1 9 8 7 ) ,a sw e l la stwoind i c a to r so fc i t a t ionin e q u a l i t yands k ewn e s sth a ta r erob u s ttoe x t r em e ob s e r v a t ion s(G ro en e v e ldand M e e d en ,1 9 8 4 ) . Th er e s u l t sa r ein T ab l e Binth e App end i x . In t e r e s t in g l yeno u gh ,th es k ewn e s sandc i t a t ionin e q u a l i t yo fth eth r e ed i s t r ib u t ion sa r eo fth es am e o rd e ro fm a gn i t ud e . IV . 2 .Th ep e r fo rm an c eo fth es t and a rdf i e ld -no rm a l i z a t ionp ro c edu r e W ec an e s t im a t eth eimp a c to fth es t and a rd f i e ld -no rm a l i z a t ion p ro c e d u r eu s in gth e m e a s u r em en tf r am ewo r kin t rod u c e din C r e spo e ta l .( 2 0 1 3 ) .W ef i r s te s t im a t eth ee f f e c tono v e r a l l c i t a t ionin e q u a l i t yth a tc anb ea t t r ib u t e dtod i f f e r en c e sinp rod u c t ionandc i t a t ionp r a c t i c e sb e tw e en c l u s t e r sth ro u ghth et e rmIDCC( I n e q u a l i t yd u etoDi f f e r en c e sinCi t a t ionimp a c tb e tw e enCl u s t e r s ) . Th en ,w ea s s e s sth ep e r fo rm an c eo fth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r eb yth er e d u c t ioni t ind u c e sinth eIDCCt e rm .Inapp l i c a t ion s ,i ti scon v en i en tto p a r t i t ione a chc l u s t e rc i t a t ion d i s t r ib u t ionin to1 0 0p e r c en t i l e s ,ind e x e db yπ=1 , . . . ,1 0 0 .G i v enth em an yc l u s t e r sw i thv e r yf ew p ub l i c a t ion s( s e eT ab l e1 ) ,w eapp l yth i sm e thodtoth ec i t a t iond i s t r ib u t ionC ’r e s t r i c t e dtoth e3 , 3 3 2 c l u s t e r sw i th mo r eth an2 5 0p ub l i c a t ion s .Th i sd i s t r ib u t ionin c l ud e s3 , 4 4 1 , 6 6 6m i l l ionp ub l i c a t io n s,o r 9 5 . 2 %o fth eto t a l . A s s um efo ra mom en tth a t ,inan yc l u s t e rj ,w ed i s r e g a rdth ec i t a t ionin e q u a l i t yw i th ine v e r y π p e r c en t i l eb ya s s i gn in gtoe v e r ya r t i c l einth a tp e r c en t i l eth em e anc i t a t iono fth ep e r c en t i l ei t s e l f ,µj. π π sth a t ,ona v e r a g e ,th ec i t a t ionimp a c to f Th ein t e rp r e t a t iono fth ef a c tth a t ,fo re x amp l e,µj =2µl i 17 c l u s t e rji stw i c ea sl a r g ea sth ec i t a t ionimp a c to fc l u s t e rlinsp i t eo fth ef a c tth a tbo thq u an t i t i e s r ep r e s en tacommonund e r l y in gph enom enon ,n am e l y ,th es am ed e g r e eo fc i t a t i o nim p a c tinbo thc l u s t e r s . π π Ino th e rwo rd s ,fo ran yπ,th ed i s t an c eb e tw e enµj andµl i sen t i r e l ya t t r ib u t ab l etoth ed i f f e r en c e sin th ep rod u c t ionandc i t a t ionp r a c t i c e sth a tp r e v a i linth etwoc l u s t e r sfo rp ub l i c a t ion sh a v in gth es am e d e g r e eo fe x c e l l en c e .Th u s ,th ec i t a t ion in e q u a l i t yb e tw e enc l u s t e r sa te a chp e r c en t i l e ,d eno t e db yI ( π) ,i s en t i r e l ya t t r ib u t ab l etoth ed i f f e r en c e sinc i t a t ionp r a c t i c e sb e tw e enth e3 , 3 3 2c l u s t e r sho ld in gcon s t an t en c e ,th et e rmIDCC ,wh i chi se q u a ltoac e r t a in th ed e g r e eo fe x c e l l en c eina l lc l u s t e r sa tq u an t i l eπ. H w e i gh t e da v e r a g eo fth e s eq u an t i t i e s,p ro v id e sagood m e a s u r eo fth eto t a limp a c tono v e r a l lc i t a t ion in e q u a l i t yth a tc anb ea t t r ib u t e dtos u chd i f f e r en c e s( fo rd e t a i l s ,s e e C r e spoe ta l . ,2 0 1 3 ) . W eu s eth er a t io ID CC/I ( C ’) ( 1 1 ) toa s s e s sth er e l a t i v ee f f e c tono v e r a l lc i t a t ionin e q u a l i t y ,I ( C ’) ,a t t r ib u t e dtoth ed i f f e r en c e sinc i t a t ion p r a c t i c e sb e tw e enc l u s t e r s .F in a l l y ,w ea r ein t e r e s t e dine s t im a t in ghowimpo r t an ts c a l ed i f f e r en c e s b e tw e enc l u s t e rc i t a t iond i s t r ib u t ion sa r eina c co un t in gfo rth ee f f e c tm e a s u r e db ye xp r e s s ion( 1 1 ) .Fo r th a tp u rpo s e ,w eu s eth er e l a t i v ech an g e inth eIDPCt e rm ,th a t i s ,th er a t io [ ID CC –ID CC* ] /ID CC, ( 1 2 ) wh e r e ID CC *i sth et e rmth a tm e a s u r e sth ee f f e c tono v e r a l lc i t a t ionin e q u a l i t ya t t r ib u t e dtoth e d i f f e r en c e s inc l u s t e rd i s t r ib u t ion sa f t e rapp l y in gth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r e . I tsho u ldb eno t e dth a t ,u s in gth es i z e -ands c a l e ind ep end en tt e chn i q u eknowna sCh a r a c t e r i s t i c S co r e sandS c a l e s ,R u i z -C a s t i l lo & W a l tm an( 2 0 1 5 )showth a t ,a sinp r e v io u sr e s e a r ch ,th e4 , 1 6 1 s i gn i f i c an tc l u s t e r sw i th mo r eth an1 0 0p ub l i c a t ion sa r eh i gh l ys k ew e dands im i l a r l yd i s t r ib u t e d .S in c e th e mo r es im i l a rc i t a t iond i s t r ib u t ion sa r e ,th eb e t t e rsho u ld wo r kan yno rm a l i z a t ionp ro c e d u r e ,w e e xp e c tr e a son ab l ygoodr e s u l t sino u rc a s e .Th ee s t im a t e so fe xp r e s s ion s( 1 1 )and( 1 2 )a r ep r e s en t e din 18 T ab l e2.Fo rcomp a r i sonp u rpo s e s ,w ein c l ud eth er e s u l t sf romC r e spoe ta l .( 2 0 1 3 )andL ie ta l .( 2 0 1 3 ) fo r2 1 9and1 7 2 Wo Ss ub f i e ld s ,r e sp e c t i v e l y . T ab l e2a roundh e r e I tc anb eob s e r v e dth a tth ee f f e c to fth ed i f f e r en c e sinc i t a t ionp r a c t i c e sb e tw e enth e3 , 3 3 2 c l u s t e r sr ep r e s en t s2 2 . 5%o fo v e r a l lc i t a t ionin e q u a l i t y ,ag r e a t e rp e r c en t a g eth anwh a th a sb e enfo und inth ep r e v io u sl i t e r a t u r efo r2 1 9o r1 7 2s ub f i e ld s .N e v e r th e l e s s ,th es t and a rdf i e ld -no rm a l i z a t ion p ro c e d u r er ed u c e sth i se f f e c tdownto4 . 3%o fth en ewo v e r a l lc i t a t iond i s t r ib u t ion ,wh i chi sq u i t ean a ch i e v em en t . Onth eo th e rh and ,f i e ld -no rm a l i z a t iong en e r a t e san8 4 . 3%r e d u c t iono fth eIDCCt e rm ,a comp a r ab l ef i g u r ew i thwh a ti sfo undinth ep r e v io u sl i t e r a t u r e .Th u s ,fo rth el a r g e s t3 , 3 3 2o fth e5 , 1 1 9 c l u s t e r s ,th ep e r fo rm an c eo fth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r e i sr e a son ab l ygood . F in a l l y ,i ti sv e r yin s t r u c t i v etos t ud yhowI ( π)ch an g e sw i thπ bo thb e fo r eanda f t e rth es t and a rd f i e ld -no rm a l i z a t ion .Th er e s u l t sapp e a rinF i g u r e1( s in c eI ( π)i sv e r yh i ghfo rπ<2 5,fo rc l a r i t yth e s e p e r c en t il e sa r eom i t t e df rom F i g u r e2 ) , wh i chw a r r an t s th efo l low in gtwocomm en t s .F i r s t l y ,th e s i gn i f i c an t imp a c to ff i e ld -no rm a l i z a t ion i sr e ad i l yapp a r en t .S e cond l y , i t i su s e f u lto in fo rm a l l yp a r t i t ion th es uppo r to fo u rc i t a t iond i s t r ib u t ion sin toth efo l low in gth r e ein t e r v a l s :[ 0 ,4 7 ] ,[ 4 8 ,9 7 ] ,and[ 9 8 , π)v a l u e sa r ev e r yh i gh .Th i sm e an sth a t ,s in c einth e s etwo 1 0 0 ] .Inth ef i r s tandth eth i rdon e ,I ( in t e r v a l sc l u s t e rc i t a t iond i s t r ib u t ion sd i f f e rb y mo r eth anas c a l ef a c to r ,th eun i v e r s a l i t ycond i t ionc an h a rd l yb es a t i s f i e dinth em . How e v e r ,I ( π)i sapp ro x im a t e l ycon s t an tfo raw id er an g eo fin t e rm e d i a t e v a l u e s inth es e cond in t e r v a l . F igu r e1a roundh e r e IV . 3 .D i f f e r en c e sb e tw e enth etwoapp ro a ch e s Insp i t eo fth egoodp e r fo rm an c eo fth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r ew esho u ldno t fo r g e tth a tth ed i f f e r en c e sinp rod u c t ionandc i t a t ionp r a c t i c e sb e tw e enc l u s t e r sr em a in in ga f t e r no rm a l i z a t iona r es t i l lr e spon s ib l efo r4 . 3%o fth eo v e r a l lc i t a t ionin e q u a l i t yI ( C ’) . Mo r eo v e r ,w e 19 sho u ldt a k ein toa c co un tth a tth e1 , 7 8 7c l u s t e r sw i thl e s sth an2 5 0p ub l i c a t ion sm u s tb eb ro u gh tb a c k in toth ean a l y s i s .Th e r e fo r e ,w ee xp e c tth a ts e t so fh i gh imp a c ta r t i c l e sb e fo r eanda f t e rth ef i e ld no rm a l i z a t ionin t rod u c e dinS e c t ionI I I . 3,n am e l y ,th es e t sX =(X1,… ,Xj ,… ,XJ)andY =(Y1,… , Yj ,… ,YJ) ,p r e s en tsom ed i f f e r en c e s wo r ths t ud y in g .A sab en chm a r k ,w ef i r s td e f in eth es e tB o f h i gh imp a c ta r t i c l e s– th a t i s ,th e1 0% mo s tc i t e da r t i c l e s– inth eo rd e r e do v e r a l lc i t a t iond i s t r ib u t ionC wh e r ea r t i c l e sf roma l lc l u s t e r sa r eo rd e r e da c co rd in gtoth e i rr awc i t a t ion sp r io rtoth eapp l i c a t iono f an yno rm a l i z a t ionp ro c e d u r e .L e tBjb eth es ub s e to fB w i tha r t i c l e s inf i e ldj ,po s s ib l yemp t yfo rm an y 8 j ,soth a t B=(B1,… , Bj ,… , BJ) . N e x t ,w ecomp a r eth es e t sX andY,and X andBf romth efo l low in g twopo in t so fv i ew . 1 .Inth ef i r s tp l a c e ,w ecomp u t eth en umb e ro fc l u s t e r swh e r eY andB a r eemp t y ,a sw e l la sth e n umb e ro fa r t i c l e sinth ein t e r s e c t ion sb e tw e enth etwop a i r s :X∩B,andX∩Y.Th er e s u l t sa r ein T ab l e3 .A . Twocomm en t sa r eino rd e r .F i r s t l y ,a l tho u ghth en umb e ro femp t yc l u s t e r sinB i s r e l a t i v e l yl a r g e ,th ep e r c en t a g eo fm i s s in ga r t i c l e si ssm a l l :on l y2 . 7%o fa l lh i gh imp a c ta r t i c l e sinX a r em i s s e dfo rth i sr e a son .Th i sp e r c en t a g ei sn e g l i g ib l efo rY.S e cond l y ,th ep e r c en t a g eo fa r t i c l e sin X∩Bi sc lo s etotwoth i rd so fth eto t a l .G i v enth ew a yB h a sb e encon s t r u c t e d ,th i si ssom ewh a t s u rp r i s in g .Int u rn ,th es e tX∩Y r ep r e s en t s9 4 . 8 %o fth eto t a l . Th u s ,on l yapp ro x im a t e l y 5%o f a r t i c l e s inX a r eno tfo und inth eno rm a l i z e ds e tY. I t i swo r thr e v i ew in gth es i t u a t ionwh enw er e s t r i c tth ea t t en t iontoth e3 , 3 3 2c l u s t e r sw i thmo r e th an2 5 0p ub l i c a t ion s ,th a ti s , wh enth eo v e r a l lc i t a t iond i s t r ib u t ioni sC ’. Th er e s u l t sfo rth e co r r e spond in gs e t sX’ ,Y’ ,andB’a r einT ab l e3 .B .Th en umb e ro femp t yc l u s t e r sinB’d e c r e a s e s 8 Du etot i e s ,a sw e l la sth ep r e s en c eo fc l u s t e r sw i thf ew e rth an1 0p ub l i c a t ion s , i t i su s u a l l yno tpo s s ib l eto m a k eane x a c t d i s t in c t ionb e tw e enp ub l i c a t ion sth a tb e lon gtoth etop1 0%andp ub l i c a t ion sth a tdono tb e lon gtoth a ts e tine v e r y c l u s t e r .Ino rd e rtoendupw i the x a c t l y1 0%topp ub l i c a t ion sinth ed a t a s e t ,w es e l e c tth etop1 0%p ub l i c a t ion sine a ch c l u s t e rfo l low in gth ef r a c t ion a lp ro c ed u r er e comm end ed in W a l tm an&S ch r e ib e r( 2 0 1 3 ) . 20 con s id e r ab l y ,wh i l e i tb e com e sz e ro inth eno rm a l i z e dc a s e .In t e r e s t in g l y ,th ep e r c en t a g e so fa r t i c l e s in th e in t e r s e c t ion sX’ ∩B’ ,and X’ ∩Y’r em a ine s s en t i a l l yth es am ea sb e fo r e . T ab l e3a roundh e r e 2 .Inth es e condp l a c e ,F i g u r e2 .Ashow sah i s to g r amo fth ed i s t r ib u t iono fth ep ropo r t iono f h i gh imp a c ta r t i c l e sinB andY o v e rth e5 , 1 1 9c l u s t e r s .A se xp e c t e d ,th ed i s t r ib u t iono fth e s e p ropo r t ion sfo rs e tBi sw a yo f fth em a r k .Th ep e r c en t a g eo fa r t i c l e sinc l u s t e rj inth ein t e r v a l[ 0 . 0 9 , 0 . 1 1 ] ,w i tha1 0%d e v i a t ionf romth ep ropo r t ion0 . 1 0 ,t a k e sp l a c einon l y2 8 2o fth e5 , 1 1 9c l u s t e r s , andin c l ud e s8 . 3 %o fa l lh i gh imp a c ta r t i c l e s .A f t e rno rm a l i z a t ion ,a l tho u ghth e s em a gn i t ud e sin cr e a s e to2 , 2 4 4c l u s t e r sandap e r c en t a g eo f5 6 . 1%a r t i c l e s ,th e ya r es t i l lno tv e r yl a r g e .F u r th e rmo r e ,an in sp e c t iono fth et a i l so fth eY h i s to g r amin F i g u r e2 .Bind i c a t e sth a t ,fo rm an yc l u s t e r s ,th e p e r c en t a g eo fa r t i c l e sinYji sno tin c l ud e dinth ein t e r v a l[ 0 . 0 5 ,0 . 1 4 5 ) .C l e a r l y ,e v ena l low in gfo r r andomv a r i a t ion ,th eimp a c to fth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r ei sf a rf romp e r f e c t.In o th e rwo rd s ,th eun i v e r s a l i t ycond i t ioni sno ts a t i s f i e d .F in a l l y,wh enw er e s t r i c tth ea t t en t iontoth e 3 , 3 3 2c l u s t e r sw i th mo r eth an2 5 0p ub l i c a t ion s ,F i g u r e2 .Ci l l u s t r a t e sth eg r e a t e rcon c en t r a t iono f c l u s t e r stow a rd sth e1 0%p e r c en t a g e .A f t e rno rm a l i z a t ion ,1 , 8 2 9c l u s t e r sin c l ud in g5 7 . 6 %o fth eto t a l a r t i c l e sa r e in c l ud e d inth e in t e r v a l[ 0 . 0 9 ,0 . 1 1 ] . F igu r e2a roundh e r e Inb r i e f ,a l tho u ghth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r e wo r k sw e l lfo rth e3 , 3 3 2c l u s t e r s w i th mo r eth an2 5 0p ub l i c a t ion s ,th eun i v e r s a l i t ycond i t ionfo rth e5 , 1 1 9c l u s t e r si sno ts a t i s f i e d .Th i s l e ad stoth econ c l u s ionth a tth es e t so fh i gh imp a c ta r t i c l e sb e fo r eanda f t e rf i e ld -no rm a l i z a t ion ,X and Y,p r e s en tsom ed i f f e r en c e s :app ro x im a t e l y5%o fa r t i c l e sinX a r eno tfo undinY,andth ep e r c en t a g e o fa r t i c l e sinac l u s t e rw i tha1 0%d e v i a t ionf rom0 . 1 0t a k e sp l a c einon l y1 , 8 2 9c l u s t e r swh i chin c l ud e 5 7 . 6%o fth eto t a ln umb e ro fa r t i c l e s . 21 IV . 4 .D i f f e r en c e sin un i v e r s i t yr ank ing s und e rth etwo so lu t ion sto a l l -s c i en c e s agg r eg a t ionp rob l em Th eun i v e r s i t yr an k in g sw i thandw i tho u tno rm a l i z a t iona c co rd in gtoth etop1 0% ind i c a to r ,Ti* andTi,anda c co rd in gtoth ea v e r a g eo fh i gh imp a c tg ap s , A *iandAi,a r ep r e s en t e d inT ab l eA inth e 9 App end i x . Un i v e r s i t i e sa r eo rd e r e da c co rd in gtoth eind i c a to r Ti. R e c a l lth a t ,und e rth ef r a c t ion a l app ro a ch ,th ea r t i c l e sa s s i gn e dtoth eun iono fth e5 0 0LRun i v e r s i t i e sr ep r e s en ton l y5 2 . 1%o fth e to t a l .N e v e r th e l e s s ,th ew e i gh t e da v e r a g eo fth eTian dTi* v a l u e sfo rth e s eun i v e r s i t i e s ,u s in ga s w e i gh t sth e i rr e l a t i v ep ub l i c a t iono u tp u t ,i s1 . 1 4and1 . 1 3 ,r e sp e c t i v e l y .S im i l a r l y ,th e s ef i g u r e sfo rth e AiandAi*v a l u e sa r e1 . 1 8and1 . 1 6 .Th i s ind i c a t e sth a tth econ t r ib u t iono fth e s eun i v e r s i t i e s i sc l e a r l y abo v eth ewo r lda v e r a g ea c co rd in gtobo th ind i c a to r s . W en e x ta r r i v etoth ek e yemp i r i c a lq u e s t iono fth ep ap e r ,n am e l y ,th econ s e q u en c e so fadop t in g th etwoso l u t ion stoth ea l l s c i en c e sa g g r e g a t ionp rob l em in t rod u c e d inS e c t ionI I I . 2 .W eb e g inw i thth e comp a r i sono fun i v e r s i t yr an k in g sa c co rd in gtoTi andT *i. Bo tht h eP e a r son andth eSp e a rm an co r r e l a t ionco e f f i c i en t sb e tw e en un i v e r s i t yv a l u e sa r e0 . 9 9 . How e v e r ,h i ghco r r e l a t ion sb e tw e en un i v e r s i t yv a l u e sandr an k s do no tp r e c l ud eimpo r t an td i f f e r en c e sfo rind i v id u a l un i v e r s i t i e s .In an a l y z in gth econ s e q u en c e so fgo in gf romTitoT *i,w em u s tt a k etwoa sp e c t sin toa c co un t .F i r s t l y ,w e sho u ldan a l y z eth er e r an k in g sth a tt a k ep l a c eins u cha mo v e .S e cond l y ,w esho u ldcomp a r eth e r t un a t e l y ,w eh a v ear e l e v an tin s t an c ew i th d i f f e r en c e sb e tw e enth eun i v e r s i t yv a l u e sth em s e l v e s .10 Fo wh i chtocomp a r eo u rr e s u l t s :th ed i f f e r en c e sfo undinR u i z -C a s t i l lo & W a l tm an( 2 0 1 5 )ingo in gf rom 9T h isi sa l soth eT op1 0%ind i c a to rcomp u t edinRu i z C a s t i l lo & W a l tm an( 2 0 1 5) .M ino rd i f f e r en c e sb e tw e enth etwo r an k in g sa r ed u etoro und ede r ro r s(Comp a r eth er an k in gund e rc l a s s i f i c a t ions y s t em8inT ab l eCinth eApp end i xinth e wo r k in gp ap e rv e r s iono fRu i z C a s t i l lo & W a l tm an–h t tp ://hd l .h and l e .n e t/ 1 0 0 1 6/ 1 8 3 8 5–w i thth er an k in ginco l umn3in T ab l eA inth eApp end i xtoth i sp ap e r ) . 1 0A spo in t edo u tb yW a l tm an e ta l .( 2 0 1 2 b) ,s in c eun i v e r s i t yv a l u ed i s t r ib u t ion sa r esom ewh a ts k ew ed ,anin c r e a s einth e r an ko faun i v e r s i t yb y ,s a y ,1 0po s i t ion si s mu ch mo r es i gn i f i c an tinth etopo fth er an k in gth anf u r th e rdownth el i s t . Th e r e fo r e ,as t a t em en ts u cha s“Un i v e r s i t yui sp e r fo rm in g2 0%b e t t e rth anun i v e r s i t y va c co rd in gtoth etop1 0%ind i c a to r ” sr an k ed2 0po s i t ion sh i gh e rth anun i v e r s i t yva c co rd in gtoth e i s mo r ein fo rm a t i v eth anas t a t em en ts u cha s“Un i v e r s i t yui top1 0% ind i c a to r . ” 22 th eun i v e r s i t yr an k in g sa c co rd in gtoTi u s in gth eW ebo fS c i en c ec l a s s i f i c a t ions y s t emw i th 2 3 6jo u rn a l s ub j e c tc a t e go r i e s ,o rs ub f i e ld s ,andth ec l a s s i f i c a t ions y s t em w ea r eu s in ginth i sp ap e rw i th5 , 1 1 9 c l u s t e r s .Th er e s u l t sfo rbo ths i t u a t ion sa r e inT ab l e4 . T ab l e4a roundh e r e A sm u cha s3 7 . 2%o fun i v e r s i t i e se xp e r i en c ev e r ysm a l lr e r an k in g so fl e s sth ano re q u a ltof i v e po s i t ion s ,wh i l e7 0un i v e r s i t i e s ,o r1 4 . 0 %o fth eto t a l,e xp e r i en c er e r an k in g sg r e a t e rth an2 5po s i t ion s . Th e s ef i g u r e sa r e2 0 . 2%and3 9 . 0%wh en go in gf romth eWo S c l a s s i f i c a t ions y s t emtoo u rd a t a s e t . Amon gth ef i r s t1 0 0un i v e r s i t i e s ,6 0e xp e r i en c esm a l lr e r an k in g singo in gf romTitoT *i,wh i l eon l y4 4 a r einth i ss i t u a t ioninth ech an g eb e tw e enc l a s s i f i c a t ions y s t em s .A sf a ra sth ec a rd in a lch an g e si s con c e rn e d ,8 2 . 8 %o fun i v e r s i t i e sh a v ech an g e s intop1 0% ind i c a to rv a l u e ssm a l l e rth ano re q u a lto0 . 0 5 wh engo in gf romTitoT *i.Th i sp e r c en t a g ei s7 1%amon gth ef i r s t1 0 0un i v e r s i t i e s .Th e s ef i g u r e sa r e 5 0 . 1 %and6 0 . 0% inth ech an g eb e tw e enc l a s s i f i c a t ions y s t em s .Fo rmo s tun i v e r s i t i e s ,th ed i f f e r en c e sa r e mo r eo r l e s sn e g l i g ib l e .A l tho u ghfo rsom eun i v e r s i t i e smo r es i gn i f i c an td i f f e r en c e sc anb eob s e r v e d ,th e con c l u s ioni sc l e a r .Th ed i f f e r en c e sob s e r v e dinun i v e r s i t yr an k in g sa c co rd in gtoth etop1 0%ind i c a to r wh en w eadop tth etwoso l u t ion sfo rso l v in gth ea l l s c i en c e sa g g r e g a t ionp rob l ema r econ s id e r ab l y f ew e rth ana c co rd in gtoth es am eind i c a to rwh enw e mo v ef romth e Wo Sc l a s s i f i c a t ions y s t emtoo u r d a t a s e t . Th er e s u l t sfo rth ecomp a r i sonb e tw e enun i v e r s i t yr an k in g sa c co rd in gtoth ea v e r a g eo fh i gh imp a c tg ap sa r einT ab l e5 .A l tho u ghas y s t em a t i ccomp a r i sonb e tw e enth eind i c a to r sTi andAii s b e yondth es cop eo fth i sp ap e r ,b ycomp a r in gth eco r r e spond in gr an k in g sinT ab l eAinth eApp end i x x t r em e th efo l low in gth r e epo in t sa r e wo r themph a s i z in g .F i r s t l y ,th el a c ko frob u s tn e s so fAitoe ob s e r v a t ion si sv e r yapp a r en t .Th efo l low in gun i v e r s i t i e sg a inal a r g en umb e ro fpo s i t ion s( inb r a c k e t s ) d u etoth eimp a c to fh i gh l y c i t e da r t i c l e s :Un i v e r s i t yo f Gö t t in g en( 2 6 4) ,th eUn i v e r s i t yo fF lo r id a( 2 0 2 ) , 23 L undUni v e r s i t y( 1 9 1 ) ,O s a k aUn i v e r s i t y( 3 1 8 ) ,andToho k uUn i v e r s i t y( 3 1 1 ) .Inth er an k in ga c co rd in g toTi,t h e s eun i v e r s i t i e so c c up ypo s i t ion s2 6 5 ,2 4 8 ,2 8 1 ,3 9 7 ,and4 0 7 ,r e sp e c t i v e l y .11 S e cond l y ,b e c a u s e th eh i gh imp a c ta r t i c l e so fc e r t a inun i v e r s i t i e sr e c e i v ec i t a t ion sc lo s etoth eCCL s ,th e ydo lo s epo s i t ion s ( inb r a c k e t s )wh enw e mo v ef romTitoAi.Th i si sth ec a s e ,fo re x amp l e ,o f Un i v e r s i t yo fT e x a s SW M e d i c a lC en t e r( loo s in g2 8 2 po s i t ion s ) , LondonS choo lo fH y g i en eand T rop i c a lM e d i c in e( 2 1 6 ) , L an c a s t e r Un i v e r s i t y( 2 2 4 ) , Un i v e r s i t yo fE x e t e r( 2 0 1 7 ) ,andP a r i sÉ co l ePo l i t e chn i q u e( 2 0 8 ) .Inth e r an k in ga c co rd in gtoTi,t h e s eun i v e r s i t i e so c c up ypo s i t ion s1 0 ,1 3 ,7 7 ,9 1 ,and9 5 ,r e sp e c t i v e l y .Th i rd l y , th er an g eo fv a r i a t ionandth ein e q u a l i t ye xh ib i t e db yAi v a l u e sa r econ s id e r ab l yg r e a t e rth antho s e e xh ib i t e db yth eTi v a l u e s .Fo re x amp l e ,th eco e f f i c i en t so fv a r i a t ionfo rth eAiandth eTi v a l u e sa r e 1 . 3 6and0 . 3 5 .Th u s ,th e r ei snodo ub tth a tbo thind i c a to r sg en e r a t econ s id e r ab l yd i f f e r en tun i v e r s i t y r an k in g s . Con s e q u en t l y ,i ti simpo r t an ttoe x am in eth econ s e q u en c e so fadop t in gth etwoso l u t ion sto th ea l l s c i en c e sa g g r e g a t ionp rob l emu s in gth ea v e r a g eo fh i gh imp a c tg ap s ind i c a to r . T ab l e5a roundh e r e Th eP e a r sonco r r e l a t ionco e f f i c i en tb e tw e enth eAi andA *i un i v e r s i t yv a l u e si s0 . 4 8 ,wh i l eth e Sp e a rm an co r r e l a t ion co e f f i c i en tb e tw e enr an k si s0 . 9 9 . How e v e r ,th elow P e a r son co r r e l a t ion co e f f i c i en ti sd u etoth ep r e s en c eo fth e Un i v e r s i t yo f Gö t t in g en . W i tho u tth i s un i v e r s i t y ,th i s co r r e l a t ionco e f f i c i en tb e com e s0 . 9 9 .Inan yc a s e ,a sb e fo r e ,h i ghco r r e l a t ion sb e tw e enun i v e r s i t yv a l u e s andr an k sdono tp r e c l ud eimpo r t an td i f f e r en c e sfo rind i v id u a lun i v e r s i t i e s .T h eo rd in a ld i f f e r en c e sin un i v e r s i t yr an k in g sa c co rd in gtoth i sind i c a to rw i thand w i tho u tf i e ld -no rm a l i z a t iona r em u chsm a l l e r th antho s eob t a in e dw i thth etop1 0%ind i c a to r .Fo re x amp l e ,6 6 . 6 %o fun i v e r s i t i e se xp e r i en c ev e r y sm a l lr e r an k in g so fl e s sth ano re q u a ltof i v epo s i t ion s , wh i l e2 0un i v e r s i t i e s ,o r4 . 0%o fth eto t a l , 1 1W eno t eth a tth eUn i v e r s i t yo f Gö t t in g eni sq u i t easp e c i a lc a s e .Th eM ean No rm a l i z edC i t a t ionS co r e ,andh en c eth eAi v a l u eo fth eUn i v e r s i t yo f Gö t t in g eni sknowntob es t ron g l yd e t e rm in edb yas in g l ee x t r em e l yh i gh l yc i t edp ub l i c a t ion( s e e W a l tm an e ta l . ,2 0 1 2 b ,fo r mo r ed e t a i l sonth i sc a s e ) . 24 e xp e r i en c er e r an k in g sg r e a t e rth an1 6po s i t ion s .Amon gth ef i r s t1 0 0un i v e r s i t i e s ,7 8e xp e r i en c esm a l l r e r an k in g s ingo in gf romAitoA *i( incomp a r i sonw i th6 0wh engo in gf romTitoT *i) . A sf a ra sth ec a rd in a lch an g e sa r econ c e rn e d ,w esho u ldr e c a l lth eh i ghco e f f i c i en to fv a r i a t iono f th e5 0 0Ai v a l u e s ,e q u a lto1 . 3 6 . How e v e r ,no rm a l i z a t ionr ad i c a l l ych an g e sth es i t u a t ion :th er an g eo f v a r i a t ionandth eco e f f i c i en to fv a r i a t iono fth eA *iv a l u e sa r enow m u chsm a l l e rth anb e fo r e( s e eT ab l e A ) . Con s e q u en t l y ,th ec a rd in a lchan g e sb e tw e enAitoA *i a r em u chl a r g e rth anb e tw e enTitoT *i: 4 1 . 8 %o fun i v e r s i t i e sh a v ech an g e s in ind i c a to rv a l u e ssm a l l e rth ano re q u a lto0 . 0 5wh engo in gf rom Ai toA *i– incomp a r i sonto8 2 . 8 % wh engo in gf romTitoT *i. V .CONCLUS IONS Th eh e t e ro g en ei t yo fth ef i e ld sd i s t in g u i sh e d inan yc l a s s i f i c a t ions y s t empo s e sa g r a v ea g g r e g a t ion p rob l emwh enon ei sin t e r e s t e dine v a l u a t in gth ec i t a t ionimp a c to fas e to fr e s e a r chun i t sinth ea l l s c i en c e sc a s e .Inth i sp ap e r ,w eh a v ean a l y z e dtwopo s s ib l eso l u t ion stoth i sp rob l em .Th ef i r s tso l u t ion r e l i e sonp r io rno rm a l i z a t iono fth er awc i t a t ion sr e c e i v e db ya l lp ub l i c a t ion s .Inp a r t i c u l a r ,w efo c u son th es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r ein wh i chf i e ld m e anc i t a t ion sa r eu s e da sno rm a l i z a t ion f a c to r s . Th es e condso l u t ione x t end sth eapp ro a chadop t e dinth eL e id enandSC Im a gor an k in g sfo r comp u t in gth eTop1 0% ind i c a to r inth ea l l s c i en c e sc a s etoan yadm i s s ib l e ind i c a to r .Th i sso l u t iondo e s no tr e q u i r ean yp r io rf i e ld -no rm a l i z a t ion :th ec i t a t ion imp a c to fan yr e s e a r chun i tinth ea l l -s c i en c e s c a s e i sc a l c u l a t e da sth eapp rop r i a t e l yw e i gh t e ds umo fth ec i t a t ion imp a c tth a tth eun i ta ch i e v e s ine a chf i e ld . Con c ep t u a l l y ,th ed i f f e r en c ei sc l e a r .Th eu s u a lso l u t ions t a r t sb yd e t e rm in in gth es e to fh i gh imp a c ta r t i c l e sinth eo v e r a l lno rm a l i z e dc i t a t iond i s t r ib u t io nfo rp ub l i c a t ion sina l lf i e ld s .G i v ena c i t a t ionind i c a to r ,t h ek e yr e f e r en c efo re a chr e s e a r chun i ti sth eun i q u eno rm a l i z e dn umb e ro fc i t a t ion s th a td e t e rm in e sth es e to fh i gh imp a c ta r t i c l e sfo ra l ls c i en c e st a k ento g e th e r .Th ea l t e rn a t i v eso l u t ion p r e s e r v e sth eun i t s ’k e yr e f e r en c ea tth el e v e lo fe a chind i v id u a lf i e ld .Ino th e r wo rd s ,th ed i f f e r en c e 25 bo i l sdowntoth ew a yth es e to fh i gh imp a c ta r t i c l e sinth ea l l s c i en c e sc a s ei scon s t r u c t e d .Inth eu s u a l so l u t ion , i t i sb u i l tup inas in g l es t ro k ea f t e rno rm a l i z a t ion .Inth ea l t e rn a t i v eso l u t ion , i t i sb u i l tupf rom th es e to fh i gh imp a c ta r t i c l e sine a chf i e ld .Inth i sc a s e ,a l lf i e ld sa r et r e a t e df a i r l yinth es en s eth a te a ch con t r ib u t e stoth eo v e r a l ls e to fh i gh imp a c ta r t i c l e s inth es am ep ropo r t ionto i t ss i z e . Inp r a c t i c e ,th e mo r ef i e ldc i t a t iond i s t r ib u t ion sd i f f e ron l yb yas c a l ef a c to r ,th eb e t t e rw i l lb eth e p e r fo rm an c eo fth es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r eine l im in a t in gth ee f f e c to fd i f f e r en c es b e tw e enf i e ldono v e r a l lc i t a t ionin e q u a l i t y ,th e mo r eth etwos e t so fh i gh imp a c ta r t i c l e sw i l lr e s emb l e e a cho th e r ,andth esm a l l e rw i l lb eth ed i f f e r en c eb e tw e enth etwoapp ro a ch e sind ep end en t l yo fth e c i t a t ion imp a c t ind i c a to rw ec a r etou s e inth ee v a l u a t iono fth er e s e a r chun i t s . U s in gal a r g e Wo Sd a t a s e tcon s i s t in go f3 . 6m i l l ionp ub l i c a t ion sinth e2 0 0 5 2 0 0 8p e r iodandan a l go r i thm i c a l l ycon s t r u c t e dp ub l i c a t ion l e v e lc l a s s i f i c a t ions y s t emth a td i s t in g u i sh e sb e tw e en5 , 1 1 9 c l u s t e r s ,t h etwoa l t e rn a t i v e sh a v eb e encon f ron t e dwh enth ec i t a t ionimp a c to fth e5 0 0LRun i v e r s i t i e s a r ee v a l u a t e du s in gtwoind i c a to r sw i thv e r yd i f f e r en tp rop e r t i e s :th e Top1 0%ind i c a to r ,andth e A v e r a g eo fh i gh imp a c tg ap s . Th esh ap eo fth ec i t a t ion d i s t r ib u t ion so f4 , 1 6 1s i gn i f i c an tc l u s t e r sw i th mo r eth an 1 0 0 p ub l i c a t ion s ino u rd a t a s e th a sb e enp r e v io u s l yshowntob eh i gh l ys k ew e dandr e a son ab l ys im i l a r(R u i z C a s t i l lo & W a l tm an ,2 0 1 5 ) .P r e v io u sr e s u l t sw i th Wo Sc l a s s i f i c a t ions y s t em sth a td i s t in g u i sha t mo s t b e tw e en2 3 5s ub f i e ld sind i c a t eth a t ,wh enth i si sth ec a s e ,th es t and a rdf i e ld -no rm a l i z a t ionp ro c e d u r e p e r fo rmsw e l linr e d u c in gth eo v e r a l lc i t a t ionin e q u a l i t ya t t r ib u t e dtoth ed i f f e r en c e sinp rod u c t ionand c i t a t ionp r a c t i c e sb e tw e enf i e ld s .Inth i sp ap e r ,w eh a v eshownth a twh enw er e s t r i c to u ra t t en t ionto 3 , 3 3 2c l u s t e r sw i th mo r eth an2 5 0p ub l i c a t ion sth i si sa l soth ec a s e .N e v e r th e l e s s , ap r i o r ii ti sno t ob v io u s wh a ttoe xp e c twh en w econ f ron tth etwo so l u t ion stoth ea l l s c i en c e sa g g r e g a t ionp rob l em w i thandw i tho u tp r io rf i e ld -no rm a l i z a t ionfo rth e5 , 1 1 9c l u s t e r s . 26 In t e r e s t in g l yeno u gh ,th ed i f f e r en c e sb e tw e enth eun i v e r s i t yr an k in g sob t a in e dw i thbo thso l u t ion s i so fasm a l lo rd e ro fm a gn i t ud eind ep end en t l yo fth ec i t a t ionimp a c tind i c a to ru s e dinth econ s t r u c t i on o fth eun i v e r s i t yr an k in g s .Inp a r t i c u l a r ,th e s ed i f f e r en c e sa r econ s id e r ab l ysm a l l e rth anth e on e s ob t a in e dinR u i z -C a s t i l lo & W a l tm an( 2 0 1 5)wh enw e mo v ef romth e Wo Sc l a s s i f i c a t ions y s t emw i th 2 3 6s ub f i e ld stoth eon eu s e d inth i sp ap e rw i th5 , 1 1 9c l u s t e r s . Inp r in c ip l e , i ts e em sp r e f e r ab l etoe v a l u a t eth ec i t a t ion imp a c to fr e s e a r chun i t s inth ea l l s c i en c e s c a s ea vo id in gan yk indo fp r io rno rm a l i z a t ionop e r a t ion . How e v e r ,th eemp i r i c a le v id en c ew eh a v e p r e s en t e dind i c a t e sth a tth em e thodr e l y in gonth ep r io rs t and a rdf i e ld -no rm a l i z a t iondo e sno tl e adto v e r yd i f f e r en tr e s u l t s .Th i si sacon v en i en tcon c l u s ion ,s in c eth e r ea r ein s t an c e swh enno rm a l i z a t ioni s s t ron g l yad v i s ab l e ;fo re x amp l e , wh en on ei sin t e r e s t e dins t ud y in gth er e s e a r ch un i t s ’c i t a t i on d i s t r ib u t ion sinth ea l l s c i en c e sc a s e– a sw edointh ecomp an ionp ap e rP e r i an e s -Rod r i g u e z &R u i z C a s t i l lo( 2 0 1 4 ) . I tsho u ldb eno t e dth a t ,b e fo r eb e in ga c c ep t e d , i two u ldb ead v i s ab l etor ep l i c a t eth er e s u l t so fth i s p ap e rfo ro th e rd a t a s e t s ,o th e rc l a s s i f i c a t ions y s t em s ,o th e rt yp e so fr e s e a r chun i t s ,ando th e rw a y so f a s s i gn in gr e spon s ib i l i t yb e tw e enr e s e a r chun i t s inth ec a s eo fco a u tho r e dp ub l i c a t ion s . 27 REFERENCES A lb a r r án ,P . ,O r t uño,I . , &Ru i z C a s t i l lo ,J .( 2 0 1 1a ) .Th em e a s u r em en to flow -andh i gh imp a c tinc i t a t iond i s t r ib u t ion s : t e chn i c a lr e s u l t s .J o u r n a lo fI n f o rm e t r i c s , 5 ,4 8 –6 3 . A lb a r r án ,P . ,C r e spo ,J . ,O r t uño ,I . ,&Ru i zC a s t i l lo ,J .( 2 0 1 1b) .Th es k ewn e s so fs c i en c ein2 1 9s ubf i e ld sandan umb e ro f a g g r e g a t e s .S c i e n t om e t r i c s, 8 8 ,3 8 5 –3 9 7 . 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Numb e ro fpub l i c a t ion s ,andc i t a t ionimp a c tind i c a to r sfo rth e5 0 0L e id enR ank ingun i v e r s i t i e s R ankT 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 5 0 5 1 Un i v e r s i t y M IT H a r v a rdUn i v P r in c e tonUn i v S t an fo rdUn i v C a l t e ch Un i vC a l i f-B e r k e l e y Un i vC a l i f-S an t aB a rb a r a Un i vC a l i f-S anF r an c i s co Y a l eUn i v Un i vT e x a s-SW M edC t r Un i vCh i c a go Un i vW a sh in g ton-S e a t t l e LondonS chH y g&T rop M ed Un i vC a l i f-S anD i e go E co l ePo l y t e chF éd é r a l eL a u s ann e No rthw e s t e rnUn i v C a rn e g i eM e l lonUn i v Un i vC a l i f-Lo sAn g e l e s Co l umb i aUn i v ETHZ u r i ch W e i zm annIn s tS c i R i c eUn i v Un i vP enn Un i vC a l i f-S an t aC r u z Un i vCo lo r ado-Bo u ld e r Un i vO x fo rd D u k eUn i v W a sh in g 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v-SUNY Un i vC a l i f-D a v i s P ennS t a t eUn i v T e chUn i vM ün ch en Un i vC in c inn a t i Y e sh i v aUn i v Un i vYo r k Un i vAm s t e rd am R u t g e r sS t a t eUn i v Un i vE a s tAn g l i a VUUn i vAm s t e rd am Un i vE x e t e r Un i vB r i t i shCo l umb i a Ind i an aUn i v-B loom in g ton U t r e ch tUn i v P a r i sT e ch-É co l ePo l y t e ch Un i vG en e v a Un i vNo t r eD am e A r i zon aS t a t eUn i v Un i vIow a G eo r g e townUn i v K a tho l i e k eUn i vL e u v en A u s t r a l i anN a t lUn i v C a s eW e s t e rnR e s e r veUn i v E indho v enUn i vT e chno l O r e gonS t a t eUn i v Un i vSh e f f i e ld Numb e ra r t i c l e s 2 6 8 1 . 1 0 1 8 6 9 . 9 7 5 3 6 2 . 9 6 5 6 8 0 . 6 2 2 1 5 8 . 4 5 2 9 9 5 . 7 2 1 0 5 9 1 . 1 0 9 9 7 0 . 5 7 2 1 0 7 . 9 5 6 5 0 6 . 7 6 1 7 9 3 . 0 3 4 4 8 9 . 9 9 3 5 6 9 . 5 8 3 8 7 5 . 4 8 3 3 3 3 . 6 6 5 4 1 3 . 6 3 5 6 3 5 . 5 3 3 4 0 7 . 9 9 2 4 4 7 . 5 7 5 1 1 7 . 3 2 2 0 3 4 . 7 4 1 9 3 8 . 1 2 4 9 7 8 . 3 3 3 4 2 5 . 5 1 1 6 2 8 6 . 5 8 1 4 7 4 . 6 9 3 9 6 7 . 3 0 4 8 9 2 . 5 2 3 2 8 8 . 9 5 9 6 2 6 . 6 7 9 5 5 8 . 6 6 4 6 8 2 . 1 6 4 8 9 3 . 6 4 2 9 1 4 . 8 0 2 5 7 7 . 9 0 6 3 3 5 . 5 2 4 4 0 5 . 1 5 1 6 1 3 . 7 8 5 1 8 9 . 5 6 1 6 1 9 . 9 5 9 7 7 6 . 6 4 3 2 2 3 . 4 3 7 4 6 3 . 7 8 1 2 9 4 . 3 8 3 9 4 4 . 6 2 2 1 3 0 . 6 8 4 3 7 8 . 2 7 5 7 5 0 . 5 5 2 2 7 6 . 9 3 8 4 9 5 . 1 6 4 1 7 7 . 7 3 5 2 1 0 . 0 5 2 7 3 7 . 8 2 3 1 1 2 . 9 0 5 1 4 6 . 7 5 ‰ 0 . 7 4 0 . 5 2 1 . 4 8 1 . 5 7 0 . 6 0 0 . 8 3 2 . 9 3 2 . 7 6 0 . 5 8 1 . 8 0 0 . 5 0 1 . 2 4 0 . 9 9 1 . 0 7 0 . 9 2 1 . 5 0 1 . 5 6 0 . 9 4 0 . 6 8 1 . 4 2 0 . 5 6 0 . 5 4 1 . 3 8 0 . 9 5 4 . 5 1 0 . 4 1 1 . 1 0 1 . 3 5 0 . 9 1 2 . 6 6 2 . 6 4 1 . 3 0 1 . 3 5 0 . 8 1 0 . 7 1 1 . 7 5 1 . 2 2 0 . 4 5 1 . 4 4 0 . 4 5 2 . 7 0 0 . 8 9 2 . 0 6 0 . 3 6 1 . 0 9 0 . 5 9 1 . 2 1 1 . 5 9 0 . 6 3 2 . 3 5 1 . 1 6 1 . 4 4 0 . 7 6 0 . 8 6 1 . 4 2 31 Top1 0% T T * R ankT * 1 . 4 8 1 . 4 0 6 3 1 . 4 7 1 . 4 2 5 9 1 . 4 6 1 . 4 4 5 5 1 . 4 4 1 . 4 1 6 0 1 . 4 4 1 . 4 9 4 6 1 . 4 4 1 . 4 3 5 6 1 . 4 3 1 . 4 1 6 1 1 . 4 2 1 . 3 6 7 2 1 . 4 2 1 . 4 2 5 8 1 . 4 2 1 . 4 4 5 4 1 . 4 2 1 . 4 4 5 3 1 . 4 1 1 . 4 1 6 2 1 . 4 1 1 . 3 6 7 4 1 . 4 0 1 . 4 0 6 5 1 . 3 9 1 . 3 1 8 2 1 . 3 9 1 . 3 7 6 9 1 . 3 9 1 . 3 5 7 5 1 . 3 8 1 . 3 7 7 0 1 . 3 7 1 . 3 8 6 7 1 . 3 7 1 . 3 2 8 1 1 . 3 6 1 . 3 3 7 7 1 . 3 6 1 . 3 1 8 3 1 . 3 5 1 . 3 1 8 6 1 . 3 5 1 . 4 0 6 4 1 . 3 5 1 . 3 2 8 0 1 . 3 5 1 . 4 3 5 7 1 . 3 5 1 . 2 7 1 0 1 1 . 3 5 1 . 3 0 8 8 1 . 3 4 1 . 3 5 7 6 1 . 3 4 1 . 3 6 7 3 1 . 3 4 1 . 3 7 7 1 1 . 3 4 1 . 3 0 9 2 1 . 3 3 1 . 3 0 8 9 1 . 3 3 1 . 2 8 9 6 1 . 3 3 1 . 3 1 8 7 1 . 3 2 1 . 2 9 9 3 1 . 3 1 1 . 3 8 6 8 1 . 3 1 1 . 2 9 9 4 1 . 3 0 1 . 2 7 9 9 1 . 3 0 1 . 3 1 8 5 1 . 3 0 1 . 3 0 9 0 1 . 2 9 1 . 3 0 9 1 1 . 2 9 1 . 2 7 1 0 0 1 . 2 8 1 . 3 9 6 6 1 . 2 8 1 . 2 8 9 8 1 . 2 8 1 . 3 1 8 4 1 . 2 7 1 . 2 9 9 5 1 . 2 7 1 . 2 7 1 0 2 1 . 2 7 1 . 2 4 1 0 9 1 . 2 6 1 . 2 6 1 0 5 1 . 2 6 1 . 2 8 9 7 1 . 2 6 1 . 2 3 1 1 1 1 . 2 5 1 . 3 3 7 8 1 . 2 5 1 . 1 9 1 3 2 1 . 2 5 1 . 2 6 1 0 3 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 1 . 6 8 1 . 6 7 1 3 7 1 4 3 1 . 5 1 1 . 5 0 2 3 3 2 4 2 1 . 3 7 1 . 4 0 7 0 7 1 1 . 4 1 1 . 4 3 5 9 6 0 1 . 4 2 1 . 5 4 2 2 3 2 0 7 1 . 3 0 1 . 4 0 1 5 9 1 5 5 1 . 5 7 1 . 6 3 2 2 2 1 1 . 3 9 1 . 3 9 2 9 2 9 1 . 6 0 1 . 6 0 1 9 4 2 0 0 1 . 3 9 1 . 4 8 5 0 4 5 2 . 1 0 2 . 2 3 1 7 1 1 6 5 1 . 5 3 1 . 5 7 8 0 7 7 1 . 1 5 1 . 1 4 1 5 1 1 5 9 1 . 5 0 1 . 5 5 9 4 1 0 0 1 . 3 4 1 . 3 5 1 3 9 1 4 0 1 . 3 5 1 . 3 9 7 1 7 0 1 . 2 7 1 . 3 0 7 2 7 4 1 . 2 5 1 . 3 3 1 4 6 1 3 9 1 . 3 0 1 . 3 7 2 1 7 2 0 3 1 . 3 2 1 . 3 1 8 1 8 2 1 . 7 7 1 . 8 3 1 8 0 1 7 8 1 . 9 8 1 . 9 8 1 6 3 1 7 2 1 . 3 8 1 . 4 0 7 8 7 9 1 . 6 7 1 . 7 7 1 0 1 9 6 1 . 3 6 1 . 3 9 1 2 1 0 1 . 3 3 1 . 3 9 3 0 1 3 0 1 1 . 2 9 1 . 2 6 1 1 4 1 1 9 1 . 2 3 1 . 2 4 9 2 9 7 1 . 3 6 1 . 4 3 1 4 0 1 3 3 1 . 2 8 1 . 3 2 3 6 3 5 1 . 4 8 1 . 5 0 2 7 2 7 1 . 2 9 1 . 3 6 9 1 8 6 1 . 1 7 1 . 1 6 1 0 0 1 0 6 1 . 3 4 1 . 3 2 1 6 0 1 7 3 1 . 2 4 1 . 2 4 2 1 6 2 1 3 1 . 2 6 1 . 2 8 6 0 6 1 1 . 4 0 1 . 4 8 8 8 8 4 1 . 5 4 1 . 5 5 2 6 4 2 6 9 1 . 2 0 1 . 2 0 8 6 9 0 1 . 2 1 1 . 2 4 2 9 8 3 0 4 1 . 2 7 1 . 3 1 3 5 3 4 1 . 1 7 1 . 2 5 1 6 8 1 6 3 1 . 2 2 1 . 2 0 4 9 5 4 1 . 5 0 1 . 6 7 3 0 3 2 9 2 1 . 4 4 1 . 4 9 1 0 2 1 0 2 1 . 4 4 1 . 5 5 2 2 2 2 0 9 1 . 9 5 1 . 7 7 5 7 6 6 1 . 1 0 1 . 1 7 8 4 8 1 1 . 1 5 1 . 1 9 2 5 1 2 4 6 1 . 3 1 1 . 3 3 3 9 4 0 1 . 3 2 1 . 3 6 1 0 6 1 0 5 1 . 2 1 1 . 2 1 8 5 8 7 1 . 2 2 1 . 3 7 1 9 5 1 7 7 1 . 2 5 1 . 2 9 1 6 1 1 6 4 1 . 1 7 1 . 2 0 9 3 9 2 R ankT 1 0 7 1 0 8 1 0 9 1 1 0 1 1 1 1 1 2 1 1 3 1 1 4 1 1 5 1 1 6 1 1 7 1 1 8 1 1 9 1 2 0 1 2 1 1 2 2 1 2 3 1 2 4 1 2 5 1 2 6 1 2 7 1 2 8 1 2 9 1 3 0 1 3 1 1 3 2 1 3 3 1 3 4 1 3 5 1 3 6 1 3 7 1 3 8 1 3 9 1 4 0 1 4 1 1 4 2 1 4 3 1 4 4 1 4 5 1 4 6 1 4 7 1 4 8 1 4 9 1 5 0 1 5 1 1 5 2 1 5 3 1 5 4 1 5 5 1 5 6 1 5 7 1 5 8 1 5 9 1 6 0 1 6 1 Un i v e r s i t y M i ch i g anS t a t eUn i v Oh ioS t a t eUn i v Un i vAb e rd e en A a rh u sUn i v M a x im i l i an sUn i vM ün ch en Un i vG l a s gow Un i vT e x a sH l thS c iC t rSAn ton io Un i vM e lbo u rn e Un i vCop enh a g en P a r i sD id e ro tUn i v Un i vS t u t t g a r t Un i vF r e ib u r g Un i vN i c eSoph i aAn t ipo l i s Un i vA r i zon a Un i vW ü r zb u r g M cM a s t e rUn i v K a r l s r uh eIn s tT e chno l Un i vB e rn No r th e a s t e rnUn i v Un i vN ew M e x ico P a r i sD e s c a r t e sUn i v M cG i l lUn i v Un i vP a r i sS ud1 1 Un i vSo u th amp ton W a k eFo r e s tUn i v Hon gKon gUn i vS c i&T e chno l Un i vNo t t in gh am Un i vD e l aw a r e Un i vQ u e en s l and Un i vM a r y l and-B a l t imo r e Un i vP a r i sE s tC r é t e i l Un i vP i e r r e& M a r i eC u r i e Un i vG ron in g en T u l an eUn i v P u rd u eUn i v-L a f a y et t e Un i vW a rw i c k F lo r id aS t a t eUn i v S to c kho lmUn i v Un i vB ath Un i vL ib r eB r u x e l l e s Un i vSC a ro l in a Un i vE r l an g enN ü rnb e r g Co lo r adoS t a t eUn i v Un i vM i am i-M i am i Un i vL i v e rpoo l K a ro l in s k aIn s t R adbo udUn i vN i jm e g en Un i vH aw a i i-M ano a Un i vL e ed s Un i vBonn Un i vR e ad in g Go e th eUn i vF r an k f u r t Un i vC a tho l i q u eLo u v a in N ew c a s t l eUn i v Mon a shUn i v Numb e ra r t i c l e s 5 9 2 3 . 0 3 9 3 3 9 . 3 5 2 7 0 0 . 2 0 5 3 9 1 . 1 3 6 3 6 2 . 3 9 4 2 2 0 . 4 1 6 0 2 . 8 5 7 2 7 8 . 9 7 7 7 6 4 . 5 7 2 6 6 2 . 0 9 2 2 0 9 . 0 5 3 7 1 9 . 6 1 1 2 3 7 . 6 9 6 4 3 4 . 6 2 3 2 0 0 . 8 9 4 9 9 1 . 5 0 3 5 9 3 . 1 4 3 6 4 0 . 7 4 1 3 5 5 . 6 3 2 7 7 9 . 7 8 2 8 3 1 . 7 2 8 4 9 1 . 3 4 4 5 5 9 . 2 2 4 7 4 6 . 2 8 2 5 8 0 . 4 7 2 8 3 5 . 5 4 5 2 6 9 . 3 6 2 8 3 3 . 8 7 6 7 1 5 . 1 1 3 6 1 4 . 6 1 8 8 4 . 3 3 6 6 5 2 . 5 2 5 4 0 5 . 1 1 1 7 8 4 . 6 4 6 6 1 9 . 3 0 2 6 1 3 . 8 4 3 0 6 8 . 6 3 2 6 1 3 . 9 2 1 8 4 6 . 1 2 2 4 9 8 . 5 7 2 5 3 9 . 8 0 4 0 3 2 . 1 6 3 3 3 5 . 5 4 4 0 2 6 . 1 5 3 7 7 8 . 5 2 6 8 9 6 . 3 2 4 9 0 5 . 5 4 2 7 4 3 . 2 7 5 1 3 3 . 1 5 3 8 8 4 . 1 2 1 9 4 7 . 9 1 3 5 3 3 . 2 1 2 8 6 3 . 3 2 3 5 6 2 . 1 6 4 9 0 1 . 9 0 ‰ 1 . 6 4 2 . 5 8 0 . 7 5 1 . 4 9 1 . 7 6 1 . 1 7 0 . 1 7 2 . 0 1 2 . 1 5 0 . 7 4 0 . 6 1 1 . 0 3 0 . 3 4 1 . 7 8 0 . 8 9 1 . 3 8 0 . 9 9 1 . 0 1 0 . 3 8 0 . 7 7 0 . 7 8 2 . 3 5 1 . 2 6 1 . 3 1 0 . 7 1 0 . 7 8 1 . 4 6 0 . 7 8 1 . 8 6 1 . 0 0 0 . 2 4 1 . 8 4 1 . 5 0 0 . 4 9 1 . 8 3 0 . 7 2 0 . 8 5 0 . 7 2 0 . 5 1 0 . 6 9 0 . 7 0 1 . 1 2 0 . 9 2 1 . 1 1 1 . 0 5 1 . 9 1 1 . 3 6 0 . 7 6 1 . 4 2 1 . 0 7 0 . 5 4 0 . 9 8 0 . 7 9 0 . 9 9 1 . 3 6 32 Top1 0% T T * R ankT * 1 . 2 4 1 . 2 5 1 0 6 1 . 2 4 1 . 2 4 1 0 8 1 . 2 4 1 . 2 0 1 2 1 1 . 2 3 1 . 1 8 1 3 6 1 . 2 3 1 . 1 9 1 3 0 1 . 2 3 1 . 2 0 1 2 2 1 . 2 3 1 . 1 6 1 4 3 1 . 2 3 1 . 2 2 1 1 3 1 . 2 3 1 . 1 9 1 3 3 1 . 2 2 1 . 2 3 1 1 2 1 . 2 2 1 . 3 3 7 9 1 . 2 2 1 . 2 0 1 2 5 1 . 2 2 1 . 1 9 1 2 9 1 . 2 1 1 . 2 1 1 1 8 1 . 2 1 1 . 1 8 1 3 4 1 . 2 1 1 . 2 2 1 1 4 1 . 2 1 1 . 2 6 1 0 4 1 . 2 0 1 . 1 7 1 3 9 1 . 2 0 1 . 2 1 1 1 9 1 . 2 0 1 . 2 0 1 2 6 1 . 1 9 1 . 1 5 1 4 8 1 . 1 9 1 . 1 7 1 4 0 1 . 1 9 1 . 2 3 1 1 0 1 . 1 9 1 . 2 2 1 1 5 1 . 1 9 1 . 1 4 1 5 5 1 . 1 9 1 . 2 4 1 0 7 1 . 1 9 1 . 2 0 1 2 8 1 . 1 8 1 . 2 0 1 2 0 1 . 1 8 1 . 1 5 1 4 6 1 . 1 8 1 . 1 4 1 5 1 1 . 1 8 1 . 2 0 1 2 7 1 . 1 8 1 . 1 9 1 3 1 1 . 1 7 1 . 1 6 1 4 4 1 . 1 7 1 . 1 3 1 6 0 1 . 1 7 1 . 2 1 1 1 6 1 . 1 7 1 . 2 0 1 2 3 1 . 1 7 1 . 2 0 1 2 4 1 . 1 7 1 . 1 7 1 4 1 1 . 1 6 1 . 2 1 1 1 7 1 . 1 6 1 . 1 4 1 5 3 1 . 1 6 1 . 1 7 1 3 8 1 . 1 5 1 . 1 4 1 5 4 1 . 1 5 1 . 1 2 1 6 4 1 . 1 5 1 . 1 2 1 6 6 1 . 1 5 1 . 1 4 1 5 7 1 . 1 4 1 . 0 8 1 9 0 1 . 1 4 1 . 1 2 1 6 5 1 . 1 4 1 . 1 4 1 5 2 1 . 1 4 1 . 1 3 1 5 8 1 . 1 4 1 . 1 4 1 5 0 1 . 1 3 1 . 1 1 1 6 8 1 . 1 3 1 . 1 1 1 7 1 1 . 1 3 1 . 1 2 1 6 2 1 . 1 3 1 . 1 4 1 5 6 1 . 1 2 1 . 1 1 1 7 0 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 1 . 1 6 1 . 2 1 7 7 7 6 1 . 2 2 1 . 2 7 3 7 3 7 1 . 2 1 1 . 1 6 2 0 1 2 2 1 1 . 0 8 1 . 0 8 9 5 1 0 3 1 . 2 2 1 . 2 2 6 5 6 5 1 . 2 7 1 . 3 0 1 0 9 1 1 1 1 . 0 2 1 . 0 0 4 6 3 4 6 9 1 . 2 8 1 . 3 1 4 7 4 6 1 . 2 4 1 . 2 2 4 4 4 7 1 . 2 5 1 . 3 2 1 9 6 1 9 0 1 . 4 9 1 . 6 2 1 9 8 1 8 7 1 . 0 9 1 . 1 2 1 5 6 1 5 6 1 . 1 6 1 . 2 0 3 5 9 3 5 8 1 . 2 3 1 . 2 7 6 2 5 9 0 . 9 7 0 . 9 8 2 2 0 2 2 0 1 . 4 8 1 . 4 8 6 9 7 2 1 . 2 8 1 . 3 6 1 3 3 1 2 2 1 . 3 4 1 . 3 2 1 1 8 1 3 0 1 . 2 7 1 . 3 6 3 3 0 3 2 0 1 . 2 5 1 . 3 4 1 8 5 1 7 9 1 . 1 4 1 . 1 3 2 0 8 2 1 6 1 . 1 6 1 . 1 8 4 2 4 2 1 . 2 6 1 . 3 3 9 9 9 5 1 . 3 1 1 . 3 2 8 7 8 8 1 . 1 6 1 . 1 5 2 2 4 2 2 8 0 . 9 4 1 . 0 5 2 4 6 2 2 9 1 . 0 3 1 . 0 7 1 0 8 1 0 7 1 . 0 4 1 . 0 8 2 2 8 2 2 4 1 . 1 3 1 . 1 3 6 7 6 9 1 . 0 1 0 . 9 9 1 7 7 1 8 5 0 . 9 2 0 . 9 6 4 3 6 4 3 3 1 . 0 4 1 . 0 9 7 6 7 5 1 . 0 5 1 . 0 6 1 0 4 1 0 4 1 . 1 6 1 . 1 5 2 9 4 2 9 9 1 . 0 8 1 . 1 6 7 3 6 7 1 . 0 6 1 . 1 0 2 3 9 2 3 5 1 . 2 4 1 . 2 8 1 6 6 1 6 6 1 . 2 3 1 . 2 2 2 0 9 2 1 7 1 . 0 0 1 . 0 7 3 1 0 3 0 5 1 . 1 2 1 . 1 6 2 3 5 2 3 2 0 . 9 9 1 . 0 2 2 6 1 2 5 9 1 . 1 6 1 . 1 8 1 2 5 1 3 1 1 . 0 6 1 . 0 4 1 8 1 1 9 5 1 . 1 8 1 . 2 0 1 2 2 1 2 7 1 . 0 2 1 . 0 2 1 6 2 1 7 0 1 . 1 4 1 . 1 1 6 3 6 8 1 . 0 6 1 . 0 7 1 1 3 1 1 3 1 . 0 8 1 . 0 6 2 2 7 2 3 3 1 . 0 5 1 . 0 7 1 1 0 1 1 0 1 . 0 8 1 . 0 9 1 4 8 1 5 3 1 . 0 9 1 . 0 9 2 9 0 2 9 4 1 . 0 7 1 . 0 9 1 6 7 1 7 4 0 . 9 5 0 . 9 6 2 4 2 2 4 5 1 . 0 6 1 . 0 8 1 6 9 1 7 5 0 . 9 8 1 . 0 3 1 2 1 1 1 8 R ankT 1 6 2 1 6 3 1 6 4 1 6 5 1 6 6 1 6 7 1 6 8 1 6 9 1 7 0 1 7 1 1 7 2 1 7 3 1 7 4 1 7 5 1 7 6 1 7 7 1 7 8 1 7 9 1 8 0 1 8 1 1 8 2 1 8 3 1 8 4 1 8 5 1 8 6 1 8 7 1 8 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8 1 9 9 2 0 0 2 0 1 2 0 2 2 0 3 2 0 4 2 0 5 2 0 6 2 0 7 2 0 8 2 0 9 2 1 0 2 1 1 2 1 2 2 1 3 2 1 4 2 1 5 2 1 6 Un i v e r s i t y Un i vO t t aw a Un i vBo rd e a u xS e g a l en T e chUn i vB e r l in H umbo ld tUn i vB e r l in RWTHA a ch enUn i v e r s i t y N a t lUn i vS in g apo r e Un i vC en tF lo r id a Un i v Mon tp e l l i e r2 Q u e en M a r yUn i vLondon Un i vG eo r g i a Un i vN ewS W a l e s V i enn aUn i vT e chno l Un i vS ydn e y Jo s ephFo u r i e rUn i v Un i vV e rmon t Un i vS u s s e x Un i vS t r a sbo u r g Ph i l ipp sUn i vM a rb u r g Un i vM an ch e s t e r Un i vConn e c t i c u t Q u e en ' sUn i v G u t enb e r gUn i vM a in z Un i vV i enn a G eo r g eW a sh in g tonUn i v Un i vSF lo r id a-T amp a No rw e g i anUn i vS c i&T e chno l P a u lS ab a t i e rUn i v M edCo l lW i s con s in T e chUn i vD r e sd en Un i vA u c k l and M a a s t r i ch tUn i v Iow aS t a t eUn i v Un i vA l ab am a-B i rm in gh am Un i vHon gKon g T e x a sA&MUn i v-Co l l e g eS tn Un i vA lb e r t a Un i vAntw e rp Ch a lm e r sUn i vT e chno l Un i vH e l s in k i Un i vT üb in g en Uni vH amb u r g Ind i an aUn i v-P u rd u e M edUn i vSC a ro l in a F r e i eUn i vB e r l in Un i vO t a go R uh rUn i vBo ch um D r e x e lUn i v G eo r g eM a sonUn i v W a sh in g tonS t a t eUn i v Un i vR e g en sb u r g Un i vD u i sb u r gE s s en H e id e lb e r gUn i v Un i vM ed& D en tN ewJ e r s e y Un i vB i rm in gh am C i t yUn i vHon gKon g Numb e ra r t i c l e s 3 7 5 7 . 3 8 1 4 3 3 . 6 7 1 8 4 2 . 1 4 4 7 9 7 . 2 9 3 5 9 6 . 6 7 9 1 5 5 . 4 8 2 1 5 3 . 0 4 2 1 1 6 . 0 8 1 8 2 4 . 7 8 4 4 9 8 . 9 2 5 1 8 8 . 4 4 1 6 1 6 . 4 9 7 4 4 8 . 8 4 2 8 0 3 . 9 0 1 8 3 6 . 3 1 1 6 3 3 . 7 0 3 1 0 1 . 5 1 2 3 1 4 . 6 1 8 2 1 3 . 3 8 4 5 1 4 . 3 9 3 1 7 5 . 8 3 2 9 5 6 . 6 7 3 3 4 5 . 8 3 2 0 5 5 . 0 4 2 9 8 5 . 6 3 2 8 7 0 . 0 2 3 6 5 8 . 6 1 2 0 4 0 . 4 8 2 9 6 5 . 3 9 3 2 3 8 . 1 1 3 2 8 3 . 2 1 4 5 6 0 . 0 0 4 5 7 7 . 5 2 5 4 2 0 . 8 0 7 1 9 5 . 1 0 7 6 2 8 . 3 9 2 4 0 1 . 8 8 1 5 6 6 . 2 2 6 2 4 5 . 5 2 4 2 6 6 . 2 9 3 4 8 3 . 3 9 3 6 3 5 . 8 8 2 3 2 5 . 9 5 4 5 5 8 . 5 6 2 6 1 2 . 8 3 3 1 2 5 . 6 0 1 9 0 0 . 9 2 1 2 4 0 . 8 2 2 9 6 4 . 1 8 2 4 7 7 . 4 3 2 6 5 8 . 1 4 5 9 1 3 . 3 3 2 9 9 1 . 3 9 5 1 3 6 . 7 0 3 0 1 9 . 8 2 ‰ 1 . 0 4 0 . 4 0 0 . 5 1 1 . 3 3 1 . 0 0 2 . 5 3 0 . 6 0 0 . 5 9 0 . 5 0 1 . 2 4 1 . 4 4 0 . 4 5 2 . 0 6 0 . 7 8 0 . 5 1 0 . 4 5 0 . 8 6 0 . 6 4 2 . 2 7 1 . 2 5 0 . 8 8 0 . 8 2 0 . 9 3 0 . 5 7 0 . 8 3 0 . 7 9 1 . 0 1 0 . 5 6 0 . 8 2 0 . 9 0 0 . 9 1 1 . 2 6 1 . 2 7 1 . 5 0 1 . 9 9 2 . 1 1 0 . 6 6 0 . 4 3 1 . 7 3 1 . 1 8 0 . 9 6 1 . 0 1 0 . 6 4 1 . 2 6 0 . 7 2 0 . 8 6 0 . 5 3 0 . 3 4 0 . 8 2 0 . 6 9 0 . 7 4 1 . 6 4 0 . 8 3 1 . 4 2 0 . 8 4 33 Top1 0% T T * R ankT * 1 . 1 2 1 . 1 1 1 7 7 1 . 1 2 1 . 1 1 1 7 5 1 . 1 2 1 . 1 8 1 3 7 1 . 1 2 1 . 0 9 1 8 3 1 . 1 2 1 . 1 3 1 5 9 1 . 1 2 1 . 1 6 1 4 5 1 . 1 1 1 . 1 5 1 4 9 1 . 1 1 1 . 1 3 1 6 1 1 . 1 1 1 . 1 5 1 4 7 1 . 1 1 1 . 1 1 1 7 4 1 . 1 0 1 . 0 8 1 9 4 1 . 1 0 1 . 1 8 1 3 5 1 . 1 0 1 . 0 9 1 8 4 1 . 1 0 1 . 1 1 1 7 6 1 . 1 0 1 . 0 4 2 2 1 1 . 1 0 1 . 0 8 1 8 8 1 . 0 9 1 . 0 7 1 9 5 1 . 0 9 1 . 0 8 1 9 2 1 . 0 9 1 . 0 8 1 8 9 1 . 0 9 1 . 0 9 1 8 5 1 . 0 9 1 . 0 7 1 9 8 1 . 0 9 1 . 0 4 2 1 2 1 . 0 9 1 . 1 1 1 6 9 1 . 0 8 1 . 0 7 1 9 6 1 . 0 8 1 . 0 3 2 2 3 1 . 0 8 1 . 1 0 1 7 8 1 . 0 8 1 . 0 8 1 9 3 1 . 0 8 1 . 0 3 2 2 6 1 . 0 8 1 . 0 9 1 8 6 1 . 0 8 1 . 0 4 2 1 3 1 . 0 8 1 . 0 2 2 3 4 1 . 0 8 1 . 0 7 1 9 9 1 . 0 8 1 . 0 3 2 2 4 1 . 0 8 1 . 0 6 2 0 1 1 . 0 7 1 . 1 1 1 7 2 1 . 0 7 1 . 0 6 2 0 6 1 . 0 7 1 . 0 1 2 4 3 1 . 0 7 1 . 1 2 1 6 3 1 . 0 7 1 . 0 3 2 2 8 1 . 0 7 1 . 0 6 2 0 4 1 . 0 7 1 . 0 6 2 0 3 1 . 0 7 1 . 0 5 2 1 0 1 . 0 7 1 . 0 2 2 3 5 1 . 0 6 1 . 0 3 2 2 9 1 . 0 6 1 . 0 1 2 4 5 1 . 0 6 1 . 0 7 2 0 0 1 . 0 6 1 . 0 5 2 0 8 1 . 0 6 1 . 1 2 1 6 7 1 . 0 6 1 . 0 3 2 2 7 1 . 0 6 1 . 0 3 2 2 5 1 . 0 6 1 . 0 9 1 8 7 1 . 0 5 1 . 0 1 2 4 9 1 . 0 5 0 . 9 8 2 6 7 1 . 0 5 1 . 0 5 2 1 1 1 . 0 5 1 . 1 7 1 4 2 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 1 . 0 1 1 . 0 3 1 6 5 1 6 8 1 . 1 4 1 . 1 4 3 3 4 3 4 1 0 . 9 9 1 . 0 5 3 1 4 3 1 1 0 . 9 7 0 . 9 7 1 2 8 1 3 4 1 . 1 2 1 . 3 5 1 5 5 1 2 6 1 . 0 4 1 . 0 8 4 5 4 3 0 . 9 8 1 . 0 9 2 9 3 2 7 8 1 . 2 8 1 . 2 7 2 4 3 2 4 9 1 . 0 7 1 . 3 3 3 0 2 2 7 3 1 . 0 2 1 . 0 3 1 3 0 1 3 6 1 . 0 6 1 . 0 7 1 0 7 1 0 9 1 . 0 0 1 . 1 1 3 3 5 3 2 7 1 . 0 2 1 . 0 5 6 6 6 4 1 . 1 0 1 . 1 5 2 2 1 2 1 0 1 . 0 1 1 . 0 2 3 0 9 3 1 8 1 . 0 8 1 . 1 1 3 1 9 3 2 4 1 . 1 4 1 . 1 5 1 8 2 1 8 6 1 . 0 2 1 . 0 5 2 7 1 2 7 5 1 . 0 5 1 . 0 9 5 4 5 3 1 . 0 0 1 . 0 2 1 3 8 1 3 7 1 . 0 1 1 . 0 4 2 1 0 2 0 8 1 . 1 0 1 . 1 3 2 0 6 2 0 4 1 . 0 4 1 . 0 9 1 8 7 1 8 4 1 . 2 9 1 . 2 8 2 4 8 2 5 2 1 . 0 6 1 . 0 7 2 1 8 2 1 5 0 . 9 7 1 . 0 2 2 3 6 2 3 0 0 . 8 8 0 . 9 2 2 1 2 2 0 2 0 . 8 1 0 . 8 1 3 3 3 3 3 9 0 . 9 1 0 . 9 5 2 4 4 2 4 0 1 . 2 5 1 . 2 5 1 5 4 1 6 1 0 . 9 8 0 . 9 8 2 1 1 2 1 4 1 . 1 2 1 . 1 4 1 1 6 1 1 5 0 . 9 3 0 . 9 2 1 4 5 1 5 2 1 . 0 7 1 . 1 1 9 7 9 9 1 . 0 4 1 . 1 1 6 8 6 2 0 . 9 3 0 . 9 7 7 4 7 3 0 . 9 6 0 . 9 7 2 7 5 2 8 1 0 . 9 0 0 . 9 3 3 6 3 3 6 3 1 . 0 3 1 . 0 3 8 3 8 5 1 . 0 1 1 . 0 3 1 4 3 1 4 7 1 . 0 8 1 . 1 0 1 7 2 1 7 1 0 . 8 8 0 . 8 8 2 1 3 2 1 2 0 . 9 5 0 . 9 1 2 8 3 2 9 5 0 . 9 4 0 . 9 5 1 4 4 1 4 8 0 . 9 7 0 . 9 7 2 5 9 2 6 3 0 . 8 9 0 . 9 6 2 3 7 2 2 6 1 . 2 3 1 . 3 0 2 7 2 2 7 2 0 . 9 6 1 . 0 5 3 9 1 3 8 2 0 . 8 9 0 . 9 0 2 5 0 2 4 8 0 . 9 3 0 . 9 5 2 7 6 2 7 9 0 . 9 4 0 . 9 8 2 6 2 2 5 6 1 . 0 4 1 . 0 6 8 9 8 9 0 . 8 6 0 . 8 4 2 5 6 2 6 6 0 . 9 4 0 . 9 4 1 2 0 1 2 8 0 . 9 1 1 . 0 4 2 4 0 2 1 9 R ankT 2 1 7 2 1 8 2 1 9 2 2 0 2 2 1 2 2 2 2 2 3 2 2 4 2 2 5 2 2 6 2 2 7 2 2 8 2 2 9 2 3 0 2 3 1 2 3 2 2 3 3 2 3 4 2 3 5 2 3 6 2 3 7 2 3 8 2 3 9 2 4 0 2 4 1 2 4 2 2 4 3 2 4 4 2 4 5 2 4 6 2 4 7 2 4 8 2 4 9 2 5 0 2 5 1 2 5 2 2 5 3 2 5 4 2 5 5 2 5 6 2 5 7 2 5 8 2 5 9 2 6 0 2 6 1 2 6 2 2 6 3 2 6 4 2 6 5 2 6 6 2 6 7 2 6 8 2 6 9 2 7 0 2 7 1 Un i v e r s i t y Un i vC l a udeB e rn a rdL yon1 Un i vBo rd e a u x1S c iT e chno l Un i vI l l ino i s-Ch i c a go V i r g in i aT e ch Un i vL e i c e s t e r S imonF r a s e rUn i v V r i j eUn i vB r u s s e l Un i vW a t e r loo Un i vW e s t e rnA u s t r a l i a Poh an gUn i vS c i&T e chno l Un i vT e x a s-M ed i c a lB r an ch K i e lUn i v V i r g in i aCommonw e a l thUn i v NC a ro l in aS t a t eUn i v H e in r i chH e in eUn i vD ü s s e ldo r f Un i v Wo l lon gon g Un i vHo u s ton-Ho u s ton Gh en tUn i v Um e åUn i v T e chUn i vD a rm s t ad t Un i vW e s t e rn On t a r io Un i vC a l g a r y Thom a sJe f f e r sonUn i v G i e s s enUn i v C a rd i f fUn i v e r s i t y H eb r ewUn i vJ e r u s a l em W a yn eS t a t eUn i v Un i v Mon t r é a l Sw edUn i vA g rS c i Un i vB e r g en Un i vO s lo Un i vF lo r id a Un i vN eb r a s k a-L in co ln Un i vAd e l a id e Un i vCo l lCo r k M edUn i vW i en D a lho u s i eUn i v Un i vCo lo gn e A i xM a r s e i l l eUn i v Un i vM ün s t e r Un i vB a r c e lon a H anno v e rM edS ch Un i vC ap eTown L a v a lUn i v F r i ed r i chS ch i l l e rUn i vJ en a Upp s a l aUn i v Un i vM i l anB i co c c a Mon tp e l l i e r1Un i v Un i vGö t t in g en Un i vB r em en Un i vV i c to r i a Un i vT enn e s s e e-Kno x v i l l e Un i vCo l lD ub l in Un i vPo l i t è cn i c aV a l èn c i a Un i vN ew c a s t l e Numb e ra r t i c l e s 3 5 5 2 . 7 0 1 9 5 2 . 9 5 5 0 3 5 . 2 2 3 9 2 7 . 5 6 2 5 9 8 . 3 6 2 1 1 2 . 2 5 1 8 6 5 . 9 6 3 9 1 9 . 2 9 3 7 0 4 . 2 4 2 4 1 3 . 9 3 2 3 7 5 . 5 7 2 6 6 8 . 9 3 2 8 0 6 . 9 3 4 8 7 8 . 5 1 2 4 7 5 . 6 7 1 5 3 9 . 7 6 2 0 4 9 . 0 9 6 6 7 1 . 6 1 2 4 4 6 . 2 2 2 0 0 2 . 4 9 4 6 4 7 . 5 0 5 1 2 8 . 0 9 2 1 2 2 . 0 6 2 0 2 6 . 4 9 3 5 2 4 . 3 7 5 5 9 6 . 6 8 3 7 8 9 . 4 0 4 7 9 0 . 2 6 1 8 3 5 . 0 9 2 5 2 2 . 7 0 5 2 3 5 . 4 1 1 0 4 9 9 . 5 4 2 9 5 0 . 0 5 2 9 7 4 . 9 6 1 7 1 3 . 4 4 2 9 9 1 . 2 9 3 0 3 6 . 5 8 2 9 5 8 . 5 0 3 4 2 9 . 3 8 3 7 6 0 . 0 0 5 5 5 7 . 7 9 1 7 5 2 . 3 6 1 9 7 0 . 3 3 3 6 1 3 . 5 9 2 6 8 9 . 3 4 4 9 1 2 . 0 1 8 1 6 . 5 8 1 0 9 2 . 5 7 3 6 4 6 . 8 2 1 3 1 1 . 9 9 1 7 9 6 . 9 4 4 3 4 5 . 5 7 2 7 6 2 . 6 5 2 2 2 5 . 8 3 1 5 3 1 . 9 4 ‰ 0 . 9 8 0 . 5 4 1 . 3 9 1 . 0 9 0 . 7 2 0 . 5 8 0 . 5 2 1 . 0 8 1 . 0 2 0 . 6 7 0 . 6 6 0 . 7 4 0 . 7 8 1 . 3 5 0 . 6 8 0 . 4 3 0 . 5 7 1 . 8 5 0 . 6 8 0 . 5 5 1 . 2 9 1 . 4 2 0 . 5 9 0 . 5 6 0 . 9 8 1 . 5 5 1 . 0 5 1 . 3 3 0 . 5 1 0 . 7 0 1 . 4 5 2 . 9 0 0 . 8 2 0 . 8 2 0 . 4 7 0 . 8 3 0 . 8 4 0 . 8 2 0 . 9 5 1 . 0 4 1 . 5 4 0 . 4 8 0 . 5 5 1 . 0 0 0 . 7 4 1 . 3 6 0 . 2 3 0 . 3 0 1 . 0 1 0 . 3 6 0 . 5 0 1 . 2 0 0 . 7 6 0 . 6 2 0 . 4 2 34 Top1 0% T T * R ankT * 1 . 0 4 1 . 0 4 2 1 4 1 . 0 4 1 . 1 0 1 7 9 1 . 0 4 1 . 0 2 2 4 0 1 . 0 4 1 . 0 7 1 9 7 1 . 0 4 1 . 0 4 2 1 7 1 . 0 4 1 . 0 8 1 9 1 1 . 0 4 1 . 0 5 2 0 7 1 . 0 4 1 . 0 9 1 8 2 1 . 0 4 1 . 0 4 2 2 0 1 . 0 3 1 . 0 9 1 8 1 1 . 0 3 0 . 9 3 2 9 8 1 . 0 3 1 . 0 0 2 5 2 1 . 0 3 0 . 9 8 2 6 4 1 . 0 3 1 . 0 6 2 0 5 1 . 0 3 1 . 0 4 2 1 8 1 . 0 3 1 . 0 4 2 2 2 1 . 0 3 1 . 1 0 1 8 0 1 . 0 3 1 . 0 2 2 3 8 1 . 0 3 0 . 9 9 2 6 0 1 . 0 2 1 . 1 1 1 7 3 1 . 0 2 1 . 0 1 2 4 4 1 . 0 2 1 . 0 0 2 5 5 1 . 0 2 0 . 9 5 2 8 3 1 . 0 2 1 . 0 2 2 3 9 1 . 0 2 0 . 9 8 2 6 6 1 . 0 2 1 . 0 1 2 4 1 1 . 0 2 1 . 0 0 2 5 4 1 . 0 2 0 . 9 7 2 7 7 1 . 0 2 0 . 9 7 2 7 8 1 . 0 1 0 . 9 9 2 5 8 1 . 0 1 1 . 0 0 2 5 0 1 . 0 1 1 . 0 1 2 4 8 1 . 0 1 1 . 0 2 2 3 2 1 . 0 1 1 . 0 3 2 3 1 1 . 0 1 1 . 0 2 2 3 6 1 . 0 1 0 . 9 8 2 7 1 1 . 0 1 1 . 0 1 2 4 7 1 . 0 1 0 . 9 8 2 6 3 1 . 0 0 1 . 0 2 2 3 3 1 . 0 0 0 . 9 8 2 7 0 1 . 0 0 0 . 9 7 2 8 0 1 . 0 0 0 . 9 6 2 8 2 1 . 0 0 0 . 9 8 2 6 5 0 . 9 9 0 . 9 7 2 7 9 0 . 9 9 1 . 0 0 2 5 1 0 . 9 9 0 . 9 8 2 6 8 0 . 9 9 1 . 0 1 2 4 2 0 . 9 9 0 . 9 3 3 0 1 0 . 9 9 0 . 9 9 2 5 6 0 . 9 8 0 . 9 7 2 7 3 0 . 9 8 1 . 0 2 2 3 7 0 . 9 8 0 . 9 9 2 6 1 0 . 9 8 0 . 9 8 2 6 9 0 . 9 8 1 . 0 4 2 1 6 0 . 9 8 1 . 0 4 2 1 9 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 1 . 0 2 1 . 0 3 1 7 8 1 8 2 1 . 1 2 1 . 1 7 2 8 5 2 8 3 0 . 9 1 0 . 9 4 1 3 2 1 3 2 0 . 8 3 0 . 8 9 2 0 5 1 9 6 0 . 9 6 0 . 9 6 2 6 3 2 7 0 0 . 9 3 0 . 9 7 2 9 9 3 0 0 1 . 0 9 1 . 1 0 2 9 6 3 0 2 0 . 8 6 0 . 9 5 1 9 3 1 8 0 0 . 9 4 0 . 9 5 1 8 6 1 9 3 0 . 8 9 0 . 9 7 2 8 9 2 8 0 0 . 8 3 0 . 8 1 3 0 0 3 1 3 0 . 9 5 0 . 9 5 2 6 0 2 6 2 1 . 0 6 1 . 0 7 2 2 5 2 2 7 0 . 9 4 1 . 0 0 1 3 4 1 2 4 0 . 9 1 0 . 9 1 2 7 9 2 8 6 0 . 9 3 0 . 9 3 3 6 1 3 6 5 0 . 8 6 0 . 9 4 3 2 1 3 1 2 0 . 9 7 0 . 9 8 8 2 8 3 0 . 8 7 0 . 8 5 2 9 1 2 9 7 0 . 9 9 1 . 0 5 2 9 7 2 9 6 0 . 9 0 0 . 9 1 1 4 7 1 5 1 0 . 9 2 0 . 9 1 1 2 6 1 3 5 0 . 8 1 0 . 7 9 3 2 8 3 3 8 0 . 9 4 0 . 9 6 3 0 5 3 0 7 0 . 9 0 0 . 9 0 2 1 5 2 1 8 0 . 9 1 0 . 9 4 1 1 5 1 1 4 0 . 8 9 0 . 8 9 1 9 2 2 0 1 0 . 9 2 0 . 9 5 1 4 1 1 3 8 0 . 8 8 0 . 8 5 3 3 7 3 4 9 1 . 1 6 1 . 1 4 2 2 9 2 3 6 0 . 8 6 0 . 8 6 1 3 5 1 4 2 0 . 8 9 0 . 9 2 4 6 4 4 0 . 8 3 0 . 8 8 2 6 6 2 5 8 0 . 8 6 0 . 8 7 2 5 7 2 6 0 0 . 8 7 0 . 8 7 3 5 2 3 5 7 0 . 9 4 0 . 9 5 2 3 4 2 3 7 0 . 8 4 0 . 8 3 2 5 8 2 6 4 0 . 9 3 0 . 9 6 2 3 8 2 3 9 0 . 9 9 1 . 0 3 1 9 0 1 8 9 0 . 8 8 0 . 9 0 1 9 7 1 9 8 0 . 9 4 0 . 9 5 1 1 2 1 1 2 0 . 8 8 0 . 8 7 3 4 5 3 5 3 0 . 9 3 0 . 9 1 3 1 1 3 2 6 0 . 9 1 0 . 8 9 1 9 9 2 1 1 0 . 8 9 0 . 9 4 2 6 9 2 6 5 0 . 9 4 0 . 9 2 1 2 9 1 4 1 0 . 9 2 0 . 9 6 4 4 5 4 4 7 0 . 9 1 0 . 8 9 4 0 9 4 1 9 2 9 . 5 0 2 . 5 2 1 5 1 0 . 9 1 0 . 9 6 3 9 0 3 8 7 0 . 8 0 0 . 8 4 3 6 0 3 5 6 0 . 9 6 0 . 9 9 1 5 0 1 4 9 0 . 9 9 0 . 9 5 2 4 1 2 5 3 1 . 0 5 1 . 1 5 2 7 4 2 6 1 0 . 8 3 0 . 8 8 3 7 8 3 7 6 R ankT 2 7 2 2 7 3 2 7 4 2 7 5 2 7 6 2 7 7 2 7 8 2 7 9 2 8 0 2 8 1 2 8 2 2 8 3 2 8 4 2 8 5 2 8 6 2 8 7 2 8 8 2 8 9 2 9 0 2 9 1 2 9 2 2 9 3 2 9 4 2 9 5 2 9 6 2 9 7 2 9 8 2 9 9 3 0 0 3 0 1 3 0 2 3 0 3 3 0 4 3 0 5 3 0 6 3 0 7 3 0 8 3 0 9 3 1 0 3 1 1 3 1 2 3 1 3 3 1 4 3 1 5 3 1 6 3 1 7 3 1 8 3 1 9 3 2 0 3 2 1 3 2 2 3 2 3 3 2 4 3 2 5 3 2 6 Un i v e r s i t y Un i vR enn e s1 K an s a sS t a t eUn i v Un i vSo u th e rnD enm a r k Yo r kUn i v Un i vB u f f a lo-SUNY Po l i t e cn i co M i l ano M a c q u a r i eUn i v Po l i t e cn i coTo r ino Un i vL i è g e L undUn i v Un i vT r i e s t e Un i vPo l i t è cn i c aC a t a l un y a Un i vGo th enb u r g Un i vRo s to c k A a l toUn i v Un i vG u e lph Ind i anIn s tT e chno lM ad r a s Un i vS u r r e y Un i vLo u i s v i l l e Un i vTo r ino Lo u ghbo ro u ghUn i v Un i vS e v i l l e Un i vP ado v a Un i vS c i&T e chno lCh in a Inn sb r u c kM edUn i v KTHRo y a lIn s tT e chno l Un i vK an s a s Ch in e s eUn i vHon gKon g Un i vA u tónom aB a r c e lon a Un i vM i l an Q u e en ' sUn i vB e l f a s t Un i vO k l ahom a N an y an gT e chno lUn i v Q u e en s l andUn i vT e chno l Un i vK en t u c k y C l em sonUn i v T emp l eUn i v Un i vU lm Un i vS t r a th c l yd eG l a s gow Un i vNo v aL i sbo a Un i vM i s sou r i-Co l umb i a Un i vP a v i a Un i vTo k yo H en r iPo in c a r éUn i v Un i vL e ip z i g Un i vZ a r a go z a Un i vA u tónom aM ad r id S a a r l andUn i v Un i vPo r to H un anUn i v Lo u i s i an aS t a t eUn i v Ko r e aAd vIn s tS c i&T e chno l Hon gKon gPo l y t e chUn i v Un i vT a sm an i a G u e r i c k eUn i vM a gd eb u r g Numb e ra r t i c l e s 1 9 9 2 . 8 4 2 0 8 0 . 5 8 1 8 3 8 . 7 0 1 6 0 8 . 1 5 3 7 1 0 . 7 6 2 0 8 7 . 1 7 1 3 2 9 . 5 2 1 6 4 4 . 4 7 2 3 3 3 . 7 7 6 8 2 5 . 6 3 1 2 1 5 . 8 6 1 7 1 1 . 7 2 4 2 0 0 . 6 1 1 6 8 2 . 1 4 2 1 0 1 . 9 7 2 8 4 6 . 2 1 1 9 2 5 . 5 3 1 8 6 6 . 5 3 2 4 1 9 . 7 2 3 4 0 2 . 6 2 1 9 4 1 . 0 7 2 2 4 3 . 7 3 5 0 2 2 . 9 6 4 8 3 3 . 6 1 1 5 0 6 . 7 3 3 1 3 5 . 0 4 3 3 2 1 . 6 6 4 6 5 2 . 1 7 4 1 3 9 . 0 7 6 0 8 1 . 8 2 2 7 4 0 . 3 6 3 0 6 0 . 2 0 5 5 7 8 . 5 2 1 4 2 7 . 7 6 4 6 8 9 . 9 7 1 8 7 3 . 0 7 2 0 3 8 . 6 4 2 3 2 5 . 4 2 1 8 2 5 . 4 0 1 2 9 0 . 3 2 4 0 2 9 . 1 9 2 0 8 2 . 0 3 1 4 6 2 3 . 3 3 1 8 0 4 . 1 6 2 9 1 5 . 1 5 2 3 8 7 . 3 3 3 6 5 3 . 1 4 1 9 4 6 . 7 1 2 8 6 3 . 2 8 1 3 8 5 . 9 3 3 2 7 6 . 9 2 3 8 3 7 . 4 5 3 5 3 9 . 8 4 1 2 7 9 . 0 0 1 5 6 2 . 5 4 ‰ 0 . 5 5 0 . 5 8 0 . 5 1 0 . 4 4 1 . 0 3 0 . 5 8 0 . 3 7 0 . 4 5 0 . 6 5 1 . 8 9 0 . 3 4 0 . 4 7 1 . 1 6 0 . 4 7 0 . 5 8 0 . 7 9 0 . 5 3 0 . 5 2 0 . 6 7 0 . 9 4 0 . 5 4 0 . 6 2 1 . 3 9 1 . 3 4 0 . 4 2 0 . 8 7 0 . 9 2 1 . 2 9 1 . 1 5 1 . 6 8 0 . 7 6 0 . 8 5 1 . 5 4 0 . 4 0 1 . 3 0 0 . 5 2 0 . 5 6 0 . 6 4 0 . 5 1 0 . 3 6 1 . 1 1 0 . 5 8 4 . 0 5 0 . 5 0 0 . 8 1 0 . 6 6 1 . 0 1 0 . 5 4 0 . 7 9 0 . 3 8 0 . 9 1 1 . 0 6 0 . 9 8 0 . 3 5 0 . 4 3 35 Top1 0% T T * R ankT * 0 . 9 8 0 . 9 7 2 7 2 0 . 9 8 0 . 9 9 2 5 7 0 . 9 7 0 . 9 3 2 9 9 0 . 9 7 1 . 0 1 2 4 6 0 . 9 7 0 . 9 5 2 8 4 0 . 9 7 1 . 0 5 2 0 9 0 . 9 6 0 . 9 7 2 7 6 0 . 9 6 1 . 0 4 2 1 5 0 . 9 6 0 . 9 4 2 9 0 0 . 9 6 0 . 9 3 3 0 2 0 . 9 6 0 . 9 7 2 7 4 0 . 9 5 1 . 0 6 2 0 2 0 . 9 5 0 . 9 2 3 0 7 0 . 9 5 0 . 9 5 2 8 9 0 . 9 5 1 . 0 3 2 3 0 0 . 9 5 0 . 8 9 3 2 3 0 . 9 4 1 . 0 0 2 5 3 0 . 9 4 0 . 9 9 2 6 2 0 . 9 3 0 . 8 8 3 2 6 0 . 9 3 0 . 8 9 3 2 5 0 . 9 3 0 . 9 7 2 7 5 0 . 9 3 0 . 9 3 3 0 0 0 . 9 2 0 . 9 5 2 8 7 0 . 9 2 0 . 9 4 2 9 4 0 . 9 2 0 . 8 7 3 3 4 0 . 9 2 0 . 9 5 2 8 5 0 . 9 2 0 . 9 2 3 0 5 0 . 9 2 0 . 9 4 2 9 2 0 . 9 2 0 . 8 9 3 2 1 0 . 9 2 0 . 9 3 2 9 7 0 . 9 2 0 . 9 4 2 9 5 0 . 9 1 0 . 9 0 3 1 7 0 . 9 1 0 . 9 9 2 5 9 0 . 9 1 0 . 9 3 3 0 3 0 . 9 1 0 . 9 0 3 1 3 0 . 9 1 0 . 9 6 2 8 1 0 . 9 0 0 . 8 9 3 1 9 0 . 9 0 0 . 9 1 3 0 9 0 . 9 0 0 . 9 3 2 9 6 0 . 8 9 0 . 9 1 3 1 1 0 . 8 9 0 . 9 1 3 0 8 0 . 8 9 0 . 9 2 3 0 4 0 . 8 8 0 . 8 9 3 2 2 0 . 8 8 0 . 8 9 3 2 4 0 . 8 8 0 . 8 7 3 3 0 0 . 8 8 0 . 9 4 2 9 1 0 . 8 7 0 . 9 0 3 1 5 0 . 8 7 0 . 8 6 3 4 2 0 . 8 7 0 . 8 7 3 3 3 0 . 8 7 0 . 9 5 2 8 6 0 . 8 6 0 . 8 6 3 3 8 0 . 8 6 0 . 9 2 3 0 6 0 . 8 6 0 . 9 5 2 8 8 0 . 8 6 0 . 8 1 3 6 1 0 . 8 6 0 . 8 8 3 2 7 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 0 . 8 8 0 . 9 1 3 2 2 3 2 3 0 . 7 1 0 . 7 8 3 5 4 3 4 2 0 . 9 6 0 . 9 4 3 2 0 3 3 3 0 . 7 9 0 . 7 9 3 7 7 3 8 6 0 . 8 8 0 . 9 0 2 0 2 2 0 6 0 . 8 4 0 . 9 4 3 2 4 3 0 6 0 . 8 3 0 . 8 5 3 9 5 3 9 6 0 . 7 8 0 . 9 0 3 7 2 3 6 1 0 . 9 5 0 . 9 5 2 8 2 2 9 0 0 . 8 9 0 . 9 0 9 0 9 3 1 . 0 0 1 . 0 3 3 8 5 3 8 8 0 . 7 5 1 . 0 2 3 7 6 3 3 1 0 . 9 7 0 . 9 6 1 5 2 1 6 2 0 . 8 0 0 . 7 7 3 6 8 3 8 1 0 . 9 0 1 . 0 3 3 0 7 2 9 1 0 . 8 0 0 . 7 2 2 7 7 3 0 3 0 . 5 1 0 . 5 7 4 1 1 4 0 5 0 . 6 7 0 . 7 4 3 8 0 3 7 1 0 . 7 3 0 . 7 1 3 2 3 3 3 4 0 . 7 6 0 . 7 6 2 5 5 2 5 7 0 . 7 2 0 . 7 6 3 6 5 3 5 9 0 . 6 9 0 . 7 2 3 4 8 3 4 4 0 . 8 1 0 . 8 7 1 5 3 1 4 6 0 . 5 9 0 . 6 4 2 3 2 2 2 3 0 . 7 2 0 . 7 3 3 9 6 4 0 4 0 . 7 2 0 . 7 7 2 7 8 2 7 4 1 . 0 2 1 . 0 2 1 9 1 1 9 7 0 . 7 8 0 . 7 8 1 7 9 1 8 3 0 . 8 5 0 . 8 6 1 8 3 1 8 8 0 . 8 2 0 . 8 2 1 1 7 1 2 0 0 . 8 5 0 . 8 8 2 7 3 2 7 7 0 . 7 3 0 . 7 4 2 8 0 2 8 5 0 . 8 4 0 . 9 0 1 2 7 1 1 7 0 . 7 3 0 . 7 4 4 0 3 4 0 8 0 . 7 9 0 . 8 1 1 7 6 1 7 6 0 . 6 9 0 . 7 3 3 7 3 3 7 2 0 . 7 6 0 . 7 7 3 4 7 3 4 8 0 . 7 9 0 . 8 0 3 1 2 3 1 9 0 . 9 3 0 . 9 7 3 3 2 3 2 8 0 . 8 4 0 . 8 4 3 9 7 4 0 6 0 . 8 5 0 . 8 7 1 8 9 1 9 2 0 . 8 8 0 . 9 4 3 1 3 3 0 8 0 . 8 9 0 . 9 0 3 1 3 3 0 . 7 1 0 . 7 4 3 7 4 3 7 7 0 . 7 4 0 . 7 6 2 8 8 2 8 7 0 . 7 5 0 . 7 8 3 1 5 3 1 7 0 . 8 9 0 . 9 3 2 0 4 1 9 9 0 . 7 4 0 . 7 8 3 5 8 3 5 4 0 . 6 6 0 . 6 7 3 0 8 3 1 4 0 . 5 2 0 . 5 6 4 5 0 4 4 8 0 . 8 2 0 . 8 5 2 4 5 2 4 3 0 . 6 9 0 . 7 4 2 4 9 2 3 8 0 . 6 9 0 . 7 4 2 6 5 2 5 4 0 . 5 9 0 . 5 6 4 4 6 4 5 5 0 . 6 7 0 . 7 1 4 0 2 4 0 1 R ankT 3 2 7 3 2 8 3 2 9 3 3 0 3 3 1 3 3 2 3 3 3 3 3 4 3 3 5 3 3 6 3 3 7 3 3 8 3 3 9 3 4 0 3 4 1 3 4 2 3 4 3 3 4 4 3 4 5 3 4 6 3 4 7 3 4 8 3 4 9 3 5 0 3 5 1 3 5 2 3 5 3 3 5 4 3 5 5 3 5 6 3 5 7 3 5 8 3 5 9 3 6 0 3 6 1 3 6 2 3 6 3 3 6 4 3 6 5 3 6 6 3 6 7 3 6 8 3 6 9 3 7 0 3 7 1 3 7 2 3 7 3 3 7 4 3 7 5 3 7 6 3 7 7 3 7 8 3 7 9 3 8 0 3 8 1 Un i v e r s i t y Un i vM an i tob a Un i vB u r g und y Un i vP a rm a Un i vF lo r en c e D a l i anUn i vT e chno l P e k in gUn i v G r i f f i thUn i v T e chn ion-I s r a e lIn s tT e chno l Un i vBo lo gn a Un i vL üb e c k T e chUn i vL i sbon L e ibn i zUn i vH anno v e r M a s s e yUn i v T e lA v i vUn i v SEUn i v Un i vT u r k u Un i vV al en c i a Ind i anIn s tT e chno lKh a r a gp u r T s in gh u aUn i v Un i vM i s s i s s ipp i S unY a t s enUn i v Un i vP e r u g i a L an zho uUn i v Un i vF e r r a r a O k l ahom aS t a t eUn i v -S t i l lw a t e r S t e l l enbo s chUn i v Un i v Mod en a&R e g g ioEm i l i a N a t lT s in gH u aUni v Un i vS an t i a god eCompo s t e l a A ub u rnUn i v N an k a iUn i v Un i vA v e i ro Un i vN an t e s Un i vB a s q u eCo un t r y A r i s to t l eUn i vTh e s s a lon i k i Un i vW i tw a t e r s r and Am i r k ab i rUn i vT e chno l Sh a r i fUn i vT e chno l H a rb inIn s tT e chno l N a t lS unY a ts enUn i v N an j in gUn i v Un i vG eno a Un i vL i sbon K yo toUn i v Un i vG r an ad a N a t lC en tUn i v Un i vN ap e l sF ed e r i coI I F ud anUn i v To k yo M ed& D en tUn i v Un i vP i s a B a rI l anUn i v Un i vE a s t e rnF in l and Un i vC a t to l i c aS a c roC uo r e L u th e rUn i vH a l l eW i t t enb e r g Pon t i f i c i aUn i vC a tó l i c aCh i l e Numb e ra r t i c l e s 3 0 1 5 . 7 9 1 3 1 0 . 6 0 1 7 4 0 . 6 8 3 8 8 9 . 8 5 2 7 9 2 . 9 1 6 3 9 1 . 9 0 1 4 5 3 . 8 4 4 9 4 7 . 9 1 5 6 3 7 . 1 8 1 2 1 7 . 2 9 2 3 3 8 . 1 2 8 7 0 . 3 3 1 4 6 6 . 5 8 6 5 7 0 . 6 1 1 7 9 6 . 2 1 2 3 0 9 . 0 6 3 5 8 8 . 4 1 2 3 5 9 . 1 3 8 3 6 1 . 9 8 1 7 0 8 . 5 1 3 3 7 2 . 9 3 1 8 0 4 . 4 6 2 3 2 5 . 1 4 1 4 2 0 . 5 7 1 5 2 3 . 4 4 1 3 9 3 . 4 9 1 6 1 0 . 2 7 3 1 1 4 . 6 4 2 6 1 8 . 8 9 2 1 1 0 . 6 5 2 8 9 3 . 0 1 1 7 0 4 . 1 2 1 3 9 8 . 2 1 2 2 8 7 . 0 7 4 1 7 3 . 9 4 1 4 5 7 . 1 4 9 3 6 . 3 3 1 4 5 3 . 7 4 3 1 9 7 . 9 3 1 5 8 8 . 2 0 4 6 3 8 . 3 1 2 5 7 4 . 4 6 1 5 5 2 . 9 5 1 1 9 2 3 . 4 6 2 7 6 4 . 7 2 1 6 6 6 . 5 7 3 9 8 3 . 8 9 5 0 7 7 . 2 7 1 6 3 5 . 6 1 3 7 3 4 . 6 6 1 7 3 5 . 9 3 1 5 2 2 . 6 4 1 5 7 6 . 3 2 1 8 1 1 . 8 8 1 1 6 9 . 1 2 ‰ 0 . 8 3 0 . 3 6 0 . 4 8 1 . 0 8 0 . 7 7 1 . 7 7 0 . 4 0 1 . 3 7 1 . 5 6 0 . 3 4 0 . 6 5 0 . 2 4 0 . 4 1 1 . 8 2 0 . 5 0 0 . 6 4 0 . 9 9 0 . 6 5 2 . 3 1 0 . 4 7 0 . 9 3 0 . 5 0 0 . 6 4 0 . 3 9 0 . 4 2 0 . 3 9 0 . 4 5 0 . 8 6 0 . 7 2 0 . 5 8 0 . 8 0 0 . 4 7 0 . 3 9 0 . 6 3 1 . 1 5 0 . 4 0 0 . 2 6 0 . 4 0 0 . 8 8 0 . 4 4 1 . 2 8 0 . 7 1 0 . 4 3 3 . 3 0 0 . 7 6 0 . 4 6 1 . 1 0 1 . 4 0 0 . 4 5 1 . 0 3 0 . 4 8 0 . 4 2 0 . 4 4 0 . 5 0 0 . 3 2 36 Top1 0% T T * R ankT * 0 . 8 6 0 . 8 7 3 3 7 0 . 8 6 0 . 8 4 3 4 9 0 . 8 6 0 . 9 0 3 1 6 0 . 8 6 0 . 8 3 3 5 8 0 . 8 6 0 . 9 0 3 1 4 0 . 8 5 0 . 8 6 3 4 3 0 . 8 5 0 . 8 9 3 2 0 0 . 8 5 0 . 8 6 3 4 0 0 . 8 5 0 . 8 7 3 2 9 0 . 8 5 0 . 8 0 3 6 4 0 . 8 5 0 . 9 4 2 9 3 0 . 8 5 0 . 9 0 3 1 2 0 . 8 5 0 . 8 3 3 5 7 0 . 8 4 0 . 8 6 3 3 9 0 . 8 4 0 . 8 3 3 5 4 0 . 8 4 0 . 8 4 3 5 2 0 . 8 4 0 . 8 4 3 5 1 0 . 8 4 0 . 9 1 3 1 0 0 . 8 3 0 . 8 7 3 3 1 0 . 8 3 0 . 8 6 3 4 1 0 . 8 3 0 . 8 3 3 5 3 0 . 8 3 0 . 7 9 3 6 6 0 . 8 3 0 . 8 7 3 3 2 0 . 8 3 0 . 8 3 3 5 5 0 . 8 3 0 . 8 5 3 4 4 0 . 8 1 0 . 8 1 3 6 0 0 . 8 1 0 . 8 4 3 4 7 0 . 8 1 0 . 8 5 3 4 6 0 . 8 1 0 . 7 9 3 6 7 0 . 8 1 0 . 8 0 3 6 3 0 . 8 0 0 . 8 8 3 2 8 0 . 8 0 0 . 8 5 3 4 5 0 . 7 9 0 . 7 7 3 7 4 0 . 7 9 0 . 8 1 3 5 9 0 . 7 8 0 . 8 1 3 6 2 0 . 7 8 0 . 7 6 3 7 7 0 . 7 8 0 . 8 7 3 3 5 0 . 7 8 0 . 8 9 3 1 8 0 . 7 8 0 . 8 4 3 5 0 0 . 7 8 0 . 8 3 3 5 6 0 . 7 7 0 . 7 7 3 7 3 0 . 7 7 0 . 7 7 3 7 5 0 . 7 7 0 . 7 5 3 8 0 0 . 7 7 0 . 7 8 3 7 0 0 . 7 6 0 . 7 8 3 7 1 0 . 7 6 0 . 8 7 3 3 6 0 . 7 6 0 . 7 3 3 8 9 0 . 7 6 0 . 7 5 3 7 8 0 . 7 6 0 . 7 5 3 8 1 0 . 7 6 0 . 7 5 3 7 9 0 . 7 6 0 . 7 8 3 6 9 0 . 7 6 0 . 7 2 3 9 4 0 . 7 5 0 . 7 3 3 9 2 0 . 7 5 0 . 7 3 3 9 1 0 . 7 5 0 . 7 3 3 8 8 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 0 . 7 2 0 . 7 4 2 8 7 2 8 8 0 . 6 7 0 . 6 9 4 2 4 4 2 6 0 . 9 2 1 . 0 0 3 3 8 3 3 2 0 . 7 5 0 . 7 5 2 3 0 2 3 1 0 . 6 9 0 . 7 4 3 0 4 2 9 8 0 . 7 4 0 . 7 6 1 2 4 1 2 5 0 . 6 5 0 . 6 3 4 1 9 4 2 4 0 . 7 6 0 . 8 4 1 7 4 1 5 7 0 . 7 4 0 . 7 8 1 4 9 1 4 5 0 . 6 8 0 . 6 6 4 3 5 4 4 3 0 . 7 3 0 . 7 7 3 3 1 3 2 5 0 . 8 3 0 . 8 9 4 5 1 4 4 9 0 . 9 9 0 . 9 4 3 5 6 3 7 0 0 . 7 0 0 . 7 4 1 3 1 1 2 3 0 . 9 9 0 . 6 2 3 1 6 3 9 9 0 . 6 9 0 . 6 7 3 3 9 3 5 1 0 . 6 8 0 . 7 0 2 6 8 2 6 8 0 . 6 5 0 . 7 2 3 4 9 3 3 5 0 . 6 9 0 . 7 4 9 8 9 1 0 . 6 7 0 . 6 9 3 9 3 3 9 3 0 . 6 5 0 . 6 8 2 8 4 2 8 4 0 . 7 5 0 . 7 7 3 6 7 3 6 9 0 . 6 4 0 . 7 3 3 5 3 3 3 7 0 . 9 9 1 . 0 3 3 6 4 3 6 2 0 . 6 4 0 . 7 1 4 1 0 4 0 7 0 . 6 4 0 . 6 7 4 2 1 4 2 2 0 . 6 4 0 . 6 8 4 0 4 4 0 3 0 . 5 7 0 . 6 2 3 1 7 3 1 0 0 . 6 6 0 . 7 0 3 2 7 3 2 2 0 . 7 1 0 . 7 3 3 5 1 3 5 2 0 . 6 0 0 . 6 1 3 2 9 3 2 9 0 . 6 3 0 . 6 8 4 0 0 3 9 4 0 . 5 7 0 . 5 9 4 3 7 4 3 5 0 . 5 8 0 . 6 1 3 6 9 3 6 8 0 . 5 3 0 . 5 8 2 8 1 2 7 6 0 . 7 5 0 . 7 6 3 9 8 4 0 2 0 . 7 9 0 . 8 4 4 4 8 4 4 6 0 . 5 3 0 . 6 2 4 4 2 4 2 8 0 . 9 0 0 . 8 8 2 3 1 2 4 1 0 . 6 1 0 . 7 5 4 1 2 3 9 2 0 . 6 9 0 . 6 2 2 1 4 2 3 4 0 . 8 4 0 . 8 6 2 8 6 2 8 9 0 . 5 5 0 . 5 9 4 3 0 4 2 3 0 . 7 2 0 . 7 5 5 6 5 5 0 . 5 7 0 . 5 8 3 4 1 3 4 3 0 . 5 2 0 . 5 9 4 2 7 4 1 5 0 . 6 6 0 . 6 7 2 5 2 2 5 1 0 . 5 9 0 . 6 1 2 2 6 2 2 2 0 . 5 4 0 . 5 4 4 2 6 4 3 1 0 . 6 6 0 . 6 7 2 6 7 2 6 7 0 . 5 6 0 . 5 8 4 1 4 4 1 2 0 . 5 5 0 . 5 3 4 3 2 4 4 2 0 . 5 7 0 . 5 7 4 2 2 4 2 7 0 . 6 8 0 . 6 8 3 8 2 3 9 0 0 . 5 2 0 . 5 4 4 6 7 4 6 7 R ankT 3 8 2 3 8 3 3 8 4 3 8 5 3 8 6 3 8 7 3 8 8 3 8 9 3 9 0 3 9 1 3 9 2 3 9 3 3 9 4 3 9 5 3 9 6 3 9 7 3 9 8 3 9 9 4 0 0 4 0 1 4 0 2 4 0 3 4 0 4 4 0 5 4 0 6 4 0 7 4 0 8 4 0 9 4 1 0 4 1 1 4 1 2 4 1 3 4 1 4 4 1 5 4 1 6 4 1 7 4 1 8 4 1 9 4 2 0 4 2 1 4 2 2 4 2 3 4 2 4 4 2 5 4 2 6 4 2 7 4 2 8 4 2 9 4 3 0 4 3 1 4 3 2 4 3 3 4 3 4 4 3 5 4 3 6 Un i v e r s i t y W uh anUn i v Un i vP a t r a s L in köp in gUn i v Un i vO u l u F l ind e r sUn i v Ind i anIn s tS c i S eo u lN a t lUn i v N a t lT e chUn i vA th en s X i am enUn i v To k yoIn s tT e chno l WV i r g in i aUn i v Un i vS a in sM a l a y s i a S ap i en z aUn i vRom a Un i vB a r iA ldo Mo ro Te x a sT e chUn i v O s a k aUn i v N a t lCh un gH s in gUn i v Un i vO v i edo N a t lT a iw anUn i v Un i vRom aTo rV e r g a t a N a t lCh i aoT un gUn i v N a go y aUn i v 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1 8 9 5 . 0 9 8 4 0 2 . 7 4 2 3 6 5 . 6 4 3 4 2 4 . 9 3 5 7 7 5 . 6 5 1 1 2 2 . 0 9 1 6 2 1 . 0 0 7 4 4 5 . 4 1 9 2 9 8 . 6 7 1 6 1 3 . 3 4 1 8 1 5 . 8 8 1 6 3 4 . 9 1 1 6 2 8 . 7 6 1 1 7 9 . 6 7 1 7 5 2 . 0 0 4 5 1 5 . 2 3 1 6 8 5 . 4 7 2 9 6 7 . 7 9 2 8 9 0 . 8 4 9 4 8 7 . 9 1 1 5 9 7 . 8 1 3 7 0 1 . 1 5 6 3 9 2 . 0 0 5 2 7 9 . 3 3 2 9 8 8 . 3 9 1 8 2 3 . 6 6 5 4 5 4 . 0 6 1 1 6 1 . 1 8 1 1 9 3 . 5 3 1 8 5 6 . 3 9 3 4 0 0 . 1 5 1 6 5 2 . 7 5 1 8 1 7 . 8 0 5 3 0 9 . 5 7 3 5 4 9 . 0 1 1 7 4 5 . 1 2 2 7 9 1 . 7 3 9 8 2 . 5 0 ‰ 0 . 9 2 0 . 6 3 0 . 6 6 0 . 5 1 0 . 3 3 0 . 8 7 2 . 6 4 0 . 5 8 0 . 4 4 1 . 5 1 0 . 5 1 0 . 3 3 1 . 7 8 0 . 6 0 0 . 5 8 2 . 6 8 0 . 5 2 0 . 5 2 2 . 3 2 0 . 6 5 0 . 9 5 1 . 6 0 0 . 3 1 0 . 4 5 2 . 0 6 2 . 5 7 0 . 4 5 0 . 5 0 0 . 4 5 0 . 4 5 0 . 3 3 0 . 4 8 1 . 2 5 0 . 4 7 0 . 8 2 0 . 8 0 2 . 6 2 0 . 4 4 1 . 0 2 1 . 7 7 1 . 4 6 0 . 8 3 0 . 5 0 1 . 5 1 0 . 3 2 0 . 3 3 0 . 5 1 0 . 9 4 0 . 4 6 0 . 5 0 1 . 4 7 0 . 9 8 0 . 4 8 0 . 7 7 0 . 2 7 37 Top1 0% T T * R ankT * 0 . 7 5 0 . 7 1 4 0 0 0 . 7 4 0 . 7 3 3 9 0 0 . 7 4 0 . 7 5 3 8 2 0 . 7 4 0 . 7 4 3 8 3 0 . 7 4 0 . 7 0 4 0 7 0 . 7 4 0 . 7 7 3 7 6 0 . 7 2 0 . 7 2 3 9 3 0 . 7 2 0 . 8 4 3 4 8 0 . 7 2 0 . 7 0 4 0 8 0 . 7 1 0 . 7 4 3 8 7 0 . 7 1 0 . 7 4 3 8 5 0 . 7 1 0 . 6 9 4 1 1 0 . 7 1 0 . 7 2 3 9 8 0 . 7 1 0 . 7 0 4 0 6 0 . 7 1 0 . 7 1 4 0 1 0 . 7 1 0 . 7 1 4 0 3 0 . 7 0 0 . 7 2 3 9 6 0 . 7 0 0 . 6 7 4 1 7 0 . 7 0 0 . 7 2 3 9 7 0 . 7 0 0 . 7 1 4 0 2 0 . 7 0 0 . 7 9 3 6 5 0 . 6 9 0 . 7 0 4 0 4 0 . 6 9 0 . 7 2 3 9 5 0 . 6 9 0 . 7 9 3 6 8 0 . 6 9 0 . 7 4 3 8 6 0 . 6 8 0 . 7 0 4 0 9 0 . 6 8 0 . 7 2 3 9 9 0 . 6 8 0 . 7 4 3 8 4 0 . 6 6 0 . 6 8 4 1 6 0 . 6 6 0 . 7 7 3 7 2 0 . 6 6 0 . 6 9 4 1 0 0 . 6 6 0 . 6 7 4 2 0 0 . 6 6 0 . 6 8 4 1 3 0 . 6 5 0 . 6 3 4 2 9 0 . 6 5 0 . 6 8 4 1 2 0 . 6 5 0 . 6 7 4 1 9 0 . 6 5 0 . 6 5 4 2 1 0 . 6 5 0 . 7 0 4 0 5 0 . 6 4 0 . 6 7 4 1 8 0 . 6 4 0 . 6 5 4 2 2 0 . 6 4 0 . 6 3 4 2 7 0 . 6 4 0 . 6 4 4 2 6 0 . 6 3 0 . 6 4 4 2 5 0 . 6 3 0 . 6 0 4 3 7 0 . 6 3 0 . 6 3 4 3 0 0 . 6 3 0 . 6 4 4 2 4 0 . 6 3 0 . 6 8 4 1 4 0 . 6 2 0 . 6 2 4 3 3 0 . 6 2 0 . 6 0 4 4 1 0 . 6 1 0 . 6 3 4 2 8 0 . 6 1 0 . 6 8 4 1 5 0 . 6 0 0 . 6 2 4 3 5 0 . 6 0 0 . 6 2 4 3 6 0 . 5 9 0 . 5 8 4 4 6 0 . 5 9 0 . 6 4 4 2 3 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 0 . 4 4 0 . 4 6 3 5 5 3 5 5 0 . 5 6 0 . 5 9 3 7 5 3 7 4 0 . 5 7 0 . 5 9 3 6 6 3 6 6 0 . 6 7 0 . 6 8 3 8 4 3 8 9 0 . 4 7 0 . 4 5 4 7 1 4 7 6 0 . 5 6 0 . 6 2 3 1 8 3 0 9 0 . 5 9 0 . 6 2 1 0 3 1 0 1 0 . 4 8 0 . 5 5 4 0 7 3 9 5 0 . 5 7 0 . 6 1 4 2 0 4 1 8 0 . 6 9 0 . 7 4 1 7 0 1 6 0 0 . 5 2 0 . 5 4 4 1 5 4 1 4 0 . 5 1 0 . 5 4 4 6 5 4 6 3 0 . 5 8 0 . 6 0 1 7 3 1 6 9 0 . 5 6 0 . 5 6 3 8 7 3 9 1 0 . 6 1 0 . 6 4 3 7 1 3 7 5 0 . 7 1 0 . 7 2 7 9 7 8 0 . 4 4 0 . 4 7 4 3 1 4 2 9 0 . 4 7 0 . 4 8 4 2 3 4 2 5 0 . 5 2 0 . 5 7 1 4 2 1 2 9 0 . 5 3 0 . 5 6 3 7 9 3 7 8 0 . 4 6 0 . 5 2 3 4 2 3 3 0 0 . 6 0 0 . 6 4 1 8 4 1 8 1 0 . 6 3 0 . 7 5 4 5 2 4 3 4 0 . 4 3 0 . 4 8 4 5 3 4 5 0 0 . 5 0 0 . 5 5 1 7 5 1 5 8 0 . 6 2 0 . 6 6 9 6 9 4 0 . 5 1 0 . 5 3 4 3 3 4 3 2 0 . 4 2 0 . 4 5 4 4 1 4 3 8 0 . 4 2 0 . 4 2 4 5 5 4 5 8 0 . 4 5 0 . 5 0 4 4 9 4 3 9 0 . 4 0 0 . 4 5 4 7 9 4 7 8 0 . 4 9 0 . 5 5 4 2 8 4 2 0 0 . 5 8 0 . 5 9 2 5 4 2 5 0 0 . 4 4 0 . 4 4 4 4 7 4 5 2 0 . 5 5 0 . 5 3 3 3 6 3 4 7 0 . 5 4 0 . 5 5 3 4 3 3 4 5 0 . 4 2 0 . 4 4 1 5 8 1 5 4 0 . 3 8 0 . 4 2 4 6 8 4 5 9 0 . 4 7 0 . 5 2 3 2 6 3 1 5 0 . 5 4 0 . 5 5 1 8 8 1 9 1 0 . 5 0 0 . 5 3 2 4 7 2 4 4 0 . 4 9 0 . 4 9 3 5 7 3 6 0 1 . 8 0 1 . 4 9 2 0 0 2 4 7 0 . 4 3 0 . 4 5 2 7 0 2 7 1 0 . 5 6 0 . 6 0 4 5 8 4 5 7 0 . 3 2 0 . 3 3 4 8 8 4 9 0 0 . 5 5 0 . 6 1 4 0 6 3 9 7 0 . 3 5 0 . 3 9 3 9 2 3 7 9 0 . 4 6 0 . 4 5 4 4 4 4 5 1 0 . 4 3 0 . 4 4 4 3 9 4 4 5 0 . 3 8 0 . 4 4 2 9 5 2 8 2 0 . 4 9 0 . 5 2 3 2 5 3 2 1 0 . 5 0 0 . 5 1 4 2 5 4 3 0 0 . 4 0 0 . 4 0 3 9 4 3 9 8 0 . 3 6 0 . 4 2 4 8 9 4 8 9 R ankT 4 3 7 4 3 8 4 3 9 4 4 0 4 4 1 4 4 2 4 4 3 4 4 4 4 4 5 4 4 6 4 4 7 4 4 8 4 4 9 4 5 0 4 5 1 4 5 2 4 5 3 4 5 4 4 5 5 4 5 6 4 5 7 4 5 8 4 5 9 4 6 0 4 6 1 4 6 2 4 6 3 4 6 4 4 6 5 4 6 6 4 6 7 4 6 8 4 6 9 4 7 0 4 7 1 4 7 2 4 7 3 4 7 4 4 7 5 4 7 6 4 7 7 4 7 8 4 7 9 4 8 0 4 8 1 4 8 2 4 8 3 4 8 4 4 8 5 4 8 6 4 8 7 4 8 8 4 8 9 4 9 0 4 9 1 Un i v e r s i t y Un i vP a l e rmo T a rb i a t Mod a r e sUn i v Ko r e aUn i v B e i j in gNo rm a lUn i v C a i roUn i v Un i vT s u k uba Ch ib aUn i v H an y an gUn i v E g eUn i v K y un gH e eUn i v S un g k y un kw anUn i v Ton g j iUn i v H i ro sh im aUn i v T i an j inUn i v S i ch u anUn i v Ch in aA g rUn i v No r thw e s t e rnPo l y t e chUn i v Ho k k aidoUn i v Un i vT eh r an Chonb u kN a t lUn i v J a g i e l lon i anUn i vK r a kow S t a t eUn i vC amp in a s Lomono so v Mo s cowS t a t eUn i v W a s ed aUn i v Ch un gn am N a t lUn i v Un i vP r e to r i a Un i vB u eno sA i r e s F edUn i vR ioG r and eS u l Ch u l a lon g ko rnUn i v S tP e t e r sb u r gS t a t eUn i v Un i vS ãoP a u lo Un i vCh i l e Ch a r le sUn i vP r a g u e B an a r a sH ind uUn i v K an a z aw aUn i v Chonn am N a t lUn i v Ch an gG un gUn i v N a t lY an gM in gUn i v Inh aUn i v K y un gpoo kN a t lUn i v Un i vF ed M in a sG e r a i s Kob eUn i v N a t lA u tonomo u sUn i vM e x i co H u a zhon gUn i vS c i&T e chnol K in gS a udUn i v F edUn i vR iod eJ an e i ro O k a y am aUn i v I s t anb u lUn i v Un i vM a l a y a Un i vB e l g r ad e F edUn i vV i ço s a F edUn i vS ãoP a u lo G a z iUn i v T eh r anUn i vM edS c i Un i vZ a g r eb Numb e ra r t i c l e s 2 1 7 8 . 7 2 9 3 4 . 3 1 3 7 7 2 . 2 1 1 5 2 4 . 8 4 1 3 9 7 . 8 6 3 4 1 5 . 3 6 2 6 7 8 . 0 8 3 0 1 4 . 9 4 1 8 6 0 . 3 7 1 4 5 3 . 4 7 3 8 4 2 . 3 0 1 4 7 5 . 4 0 3 4 8 8 . 4 9 2 6 9 2 . 0 5 3 6 1 2 . 1 9 1 6 9 1 . 9 8 1 2 0 8 . 4 3 6 4 6 3 . 4 8 1 9 8 6 . 6 6 1 3 2 4 . 5 1 2 3 8 7 . 2 0 4 1 9 1 . 2 6 2 8 4 1 . 2 6 1 8 8 3 . 8 4 1 4 3 2 . 6 4 1 3 3 5 . 3 4 3 0 8 7 . 4 6 2 5 5 5 . 7 8 1 7 0 7 . 0 3 8 8 9 . 7 8 1 0 6 9 0 . 1 9 1 9 3 5 . 2 3 3 6 8 8 . 1 8 1 2 7 1 . 2 7 2 0 1 4 . 7 0 1 8 4 1 . 8 6 1 9 0 9 . 0 7 1 8 9 5 . 9 9 2 0 6 3 . 4 1 2 1 2 2 . 7 7 2 0 1 9 . 7 9 2 5 3 9 . 5 1 5 1 8 2 . 2 9 3 8 4 0 . 6 9 8 7 8 . 8 5 3 2 2 1 . 9 6 3 0 0 7 . 1 9 2 7 3 9 . 4 3 1 1 1 5 . 7 8 2 2 3 1 . 3 5 5 0 6 . 1 7 1 8 0 6 . 3 2 1 9 9 1 . 2 0 1 0 7 6 . 2 0 2 0 3 8 . 5 8 ‰ 0 . 6 0 0 . 2 6 1 . 0 4 0 . 4 2 0 . 3 9 0 . 9 4 0 . 7 4 0 . 8 3 0 . 5 1 0 . 4 0 1 . 0 6 0 . 4 1 0 . 9 7 0 . 7 4 1 . 0 0 0 . 4 7 0 . 3 3 1 . 7 9 0 . 5 5 0 . 3 7 0 . 6 6 1 . 1 6 0 . 7 9 0 . 5 2 0 . 4 0 0 . 3 7 0 . 8 5 0 . 7 1 0 . 4 7 0 . 2 5 2 . 9 6 0 . 5 4 1 . 0 2 0 . 3 5 0 . 5 6 0 . 5 1 0 . 5 3 0 . 5 2 0 . 5 7 0 . 5 9 0 . 5 6 0 . 7 0 1 . 4 3 1 . 0 6 0 . 2 4 0 . 8 9 0 . 8 3 0 . 7 6 0 . 3 1 0 . 6 2 0 . 1 4 0 . 5 0 0 . 5 5 0 . 3 0 0 . 5 6 38 Top1 0% T T * R ankT * 0 . 5 8 0 . 5 7 4 4 7 0 . 5 8 0 . 5 8 4 4 5 0 . 5 8 0 . 5 9 4 4 2 0 . 5 8 0 . 6 2 4 3 1 0 . 5 7 0 . 6 0 4 3 8 0 . 5 7 0 . 5 9 4 4 3 0 . 5 7 0 . 5 6 4 5 0 0 . 5 7 0 . 6 2 4 3 4 0 . 5 6 0 . 5 5 4 5 4 0 . 5 6 0 . 5 7 4 4 8 0 . 5 6 0 . 5 4 4 5 5 0 . 5 6 0 . 6 2 4 3 2 0 . 5 6 0 . 5 5 4 5 3 0 . 5 5 0 . 5 7 4 4 9 0 . 5 5 0 . 6 0 4 3 9 0 . 5 5 0 . 5 6 4 5 2 0 . 5 4 0 . 5 9 4 4 4 0 . 5 4 0 . 5 4 4 5 7 0 . 5 4 0 . 6 0 4 4 0 0 . 5 2 0 . 5 6 4 5 1 0 . 5 2 0 . 5 3 4 6 0 0 . 5 2 0 . 5 3 4 5 8 0 . 5 2 0 . 5 3 4 5 9 0 . 5 1 0 . 5 1 4 6 5 0 . 5 1 0 . 5 4 4 5 6 0 . 5 1 0 . 5 1 4 6 3 0 . 5 1 0 . 5 0 4 6 7 0 . 5 1 0 . 5 1 4 6 4 0 . 5 1 0 . 4 9 4 7 2 0 . 5 0 0 . 5 2 4 6 2 0 . 5 0 0 . 5 1 4 6 6 0 . 4 8 0 . 4 9 4 7 0 0 . 4 8 0 . 5 2 4 6 1 0 . 4 8 0 . 5 0 4 6 8 0 . 4 8 0 . 4 6 4 8 0 0 . 4 8 0 . 4 7 4 7 5 0 . 4 8 0 . 4 7 4 7 7 0 . 4 7 0 . 4 3 4 8 9 0 . 4 7 0 . 4 9 4 7 1 0 . 4 7 0 . 4 7 4 7 8 0 . 4 6 0 . 4 9 4 6 9 0 . 4 6 0 . 4 7 4 7 6 0 . 4 6 0 . 4 8 4 7 4 0 . 4 5 0 . 4 5 4 8 1 0 . 4 4 0 . 4 9 4 7 3 0 . 4 4 0 . 4 6 4 7 9 0 . 4 4 0 . 4 3 4 8 6 0 . 4 4 0 . 4 5 4 8 2 0 . 4 4 0 . 4 3 4 8 8 0 . 4 2 0 . 4 4 4 8 5 0 . 4 2 0 . 4 4 4 8 4 0 . 4 1 0 . 3 8 4 9 5 0 . 4 1 0 . 4 4 4 8 3 0 . 4 0 0 . 4 0 4 9 1 0 . 4 0 0 . 4 3 4 8 7 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 0 . 4 6 0 . 4 7 4 0 8 4 1 0 0 . 3 2 0 . 3 0 4 9 4 4 9 5 0 . 4 2 0 . 4 5 3 4 4 3 3 6 0 . 3 8 0 . 4 0 4 6 9 4 6 8 0 . 3 8 0 . 4 1 4 7 5 4 7 2 0 . 4 6 0 . 4 8 3 4 0 3 4 0 0 . 3 9 0 . 3 8 4 0 5 4 1 1 0 . 4 0 0 . 4 3 3 8 9 3 8 0 0 . 3 3 0 . 3 4 4 6 4 4 6 4 0 . 3 2 0 . 3 2 4 8 4 4 8 3 0 . 3 2 0 . 3 3 3 8 3 3 8 5 0 . 3 6 0 . 4 0 4 7 4 4 7 0 0 . 4 1 0 . 4 1 3 6 2 3 6 4 0 . 3 5 0 . 3 5 4 1 7 4 2 1 0 . 3 4 0 . 3 8 3 8 8 3 7 3 0 . 3 7 0 . 3 7 4 6 1 4 6 6 0 . 2 9 0 . 3 5 4 9 0 4 8 7 0 . 4 0 0 . 4 0 2 5 3 2 5 5 0 . 4 3 0 . 4 2 4 2 9 4 3 6 0 . 3 5 0 . 3 8 4 8 5 4 8 0 0 . 4 0 0 . 4 2 4 1 3 4 1 3 0 . 3 6 0 . 3 8 3 5 0 3 4 6 0 . 4 6 0 . 4 9 3 7 0 3 6 7 0 . 4 1 0 . 4 3 4 4 3 4 4 1 0 . 3 3 0 . 3 3 4 8 3 4 8 1 0 . 3 5 0 . 3 4 4 8 6 4 8 5 0 . 3 5 0 . 3 6 3 9 9 4 0 0 0 . 3 7 0 . 3 8 4 1 8 4 1 7 0 . 3 0 0 . 3 1 4 7 7 4 7 7 0 . 3 6 0 . 3 8 4 9 2 4 9 2 0 . 3 6 0 . 3 6 1 6 4 1 6 7 0 . 2 9 0 . 3 0 4 7 0 4 7 1 0 . 3 4 0 . 3 5 3 8 1 3 8 4 0 . 4 1 0 . 4 3 4 7 6 4 7 5 0 . 3 2 0 . 3 3 4 6 0 4 6 1 0 . 3 3 0 . 3 4 4 6 6 4 6 5 0 . 2 5 0 . 2 3 4 8 1 4 8 6 0 . 2 6 0 . 2 5 4 7 8 4 8 2 0 . 2 6 0 . 2 8 4 7 3 4 7 3 0 . 3 7 0 . 3 8 4 3 8 4 4 0 0 . 3 4 0 . 3 6 4 5 4 4 5 3 0 . 3 7 0 . 3 8 4 1 6 4 1 6 0 . 3 7 0 . 3 6 3 0 6 3 1 6 0 . 3 2 0 . 3 4 3 8 6 3 8 3 0 . 3 2 0 . 3 6 4 9 5 4 9 3 0 . 4 8 0 . 4 8 3 4 6 3 5 0 0 . 3 5 0 . 3 5 4 0 1 4 0 9 0 . 3 0 0 . 3 0 4 3 4 4 3 7 0 . 2 8 0 . 2 6 4 9 3 4 9 4 0 . 2 8 0 . 3 0 4 6 2 4 6 2 0 . 2 4 0 . 2 2 5 0 0 5 0 0 0 . 2 6 0 . 2 5 4 8 0 4 8 4 0 . 2 4 0 . 2 6 4 8 2 4 7 9 0 . 2 1 0 . 2 0 4 9 7 4 9 9 0 . 3 2 0 . 3 3 4 5 9 4 6 0 R ankT 4 9 2 4 9 3 4 9 4 4 9 5 4 9 6 4 9 7 4 9 8 4 9 9 5 0 0 Un i v e r s i t y Un i vN a c lL aP l a t a Un i vE s t ad u a lP a u l i s t a N ihonUn i v An k a r aUn i v P u s anN a t lUn i v H a c e t t ep eUn i v Kon k u kUn i v F edUn i vP a r an á C a tho l i cUn i vKo r e a Un iono fL e id enR an k in g un i v e r s i t i e s A v e r a g eo v e rth e5 0 0v a l u e s SD CV Top1 0% T T * R ankT * 0 . 3 9 0 . 4 0 4 9 2 0 . 3 9 0 . 4 1 4 9 0 0 . 3 9 0 . 3 9 4 9 3 0 . 3 8 0 . 3 8 4 9 4 0 . 3 7 0 . 3 8 4 9 6 0 . 3 6 0 . 3 6 4 9 7 0 . 3 6 0 . 3 5 4 9 8 0 . 3 6 0 . 3 3 5 0 0 0 . 3 5 0 . 3 5 4 9 9 A v e r ag eh ighimp a c tg ap s A A * R ankA R ankA * 0 . 2 4 0 . 2 4 4 9 1 4 9 1 0 . 2 6 0 . 2 7 4 5 7 4 5 6 0 . 2 5 0 . 2 7 4 7 2 4 7 4 0 . 2 1 0 . 2 1 4 8 7 4 8 8 0 . 3 1 0 . 3 3 4 5 6 4 5 4 0 . 2 9 0 . 2 9 4 4 0 4 4 4 0 . 2 1 0 . 2 1 4 9 6 4 9 6 0 . 2 4 0 . 2 6 4 9 8 4 9 7 0 . 1 8 0 . 1 9 4 9 9 4 9 8 5 2 0 . 7 9 1 . 1 4 1 . 1 3 1 . 1 8 1 . 1 6 1 . 0 4 0 . 7 7 0 . 7 4 1 . 0 1 0 . 3 6 0 . 3 5 1 . 0 1 0 . 3 5 0 . 3 5 1 . 0 1 1 . 3 7 1 . 3 6 0 . 9 8 0 . 5 2 0 . 5 2 Numb e ra r t i c l e s 1 4 0 2 . 4 1 2 5 8 5 . 9 1 2 1 1 4 . 8 6 2 0 3 4 . 9 2 2 1 8 1 . 5 2 2 7 4 5 . 6 0 1 2 3 8 . 6 7 9 2 0 . 7 0 1 2 2 3 . 5 4 ‰ 0 . 3 9 0 . 7 2 0 . 5 9 0 . 5 6 0 . 6 0 0 . 7 6 0 . 3 4 0 . 2 5 0 . 3 4 1 8 8 2 3 7 0 . 3 3 3 7 6 4 . 7 4 2 7 7 5 . 2 1 0 . 7 4 39 T ab l eB . Ch a r a c t e r i s t i c so fo v e r a l lc i t a t iond i s t r ibu t ion sfo rth een t i r ed a t a s e to fd i s t in c ta r t i c l e s( 3 . 6m i l l ion ) , d i s t in c ta r t i c l e sw i tha tl e a s ton eLRun i v e r s i t y( 2 . 4m i l l ion ) ,andth ef r a c t ion a lcoun t ingfo rLRun i v e r s i t i e s( 1 . 9 m i l l ion ) D i s t r ibu t ion s F i r s tm e an S e cond m e an µ1 µ2 P e r c en t ag eo fa r t i c l e sinc a t ego r y :P e r c en t ag eo fc i t a t ion sinc a t ego r y : 1 2 3 1 2 3 3 . 6m i l l ion 8 . 7 2 4 . 0 7 2 . 0 2 0 . 2 7 . 8 2 2 . 6 3 2 . 2 4 5 . 2 2 . 4m i l l ion 9 . 8 2 6 . 5 7 1 . 5 2 0 . 8 7 . 7 2 3 . 0 3 2 . 9 4 4 . 1 1 . 9m i l l ion 9 . 8 2 5 . 0 7 0 . 9 2 0 . 7 8 . 4 2 6 . 3 3 1 . 6 4 2 . 1 D i s t r ibu t ion s Robu s tco e f f i c i en t o fv a r i a t ion GMind ex o fsk ewn e s s 3 . 6m i l l ion 0 . 7 5 0 . 6 4 2 , 4m i l l ion 0 . 7 5 0 . 7 1 1 . 9m i l l ion 0 . 9 4 0 . 7 5 µ1 = m e anc i t a t ion µ2 = m e anc i t a t iono fa r t i c l e sw i thc i t a t ion sabo v eµ1 C a t ego r y1=a r t i c l e sw i tha lowc i t a t ion ,b e lowµ1 C a t ego r y2=a r t i c l e sw i thaf a i rn umb e ro fc i t a t ion s,abo v e µ1andb e lowµ2 C a t ego r y3=a r t i c l e sw i thar em a r k ab l eo ro u t s t and in gn umb e ro fc i t a t ion s,abo v e µ2 40 T ab l e1 .M e an numb e ro fpub l i c a t ion sp e rc lu s t e r ,m,andm e an c i t a t ionp e rpub l i ca t ion ,µ,inth ep a r t i t ionb y d e c i l e so fth eo v e r a l lc i t a t iond i s t r ibu t ion m µ D e c i l e s 1 2 , 4 7 2 . 7 1 0 . 5 2 1 , 4 3 5 . 3 9 . 4 3 1 , 0 1 5 . 9 8 . 0 4 7 3 7 . 3 7 . 4 5 5 4 2 . 1 6 . 9 6 3 7 7 . 4 5 . 8 7 2 5 0 . 8 5 . 1 8 1 5 1 . 3 4 . 5 9 7 0 . 5 3 . 7 1 0 6 . 0 1 . 2 A.Numb e ro fc lu s t e r s 5 , 1 1 9 a B .Numb e ro fsm a l lc lu s t e r s 8 5 8 b C .Numb e ro fs ign i f i c an tc lu s t e r s 4 , 1 6 1 D . %o fa r t i c l e sinsm a l lc lu s t e r s 0 . 8 9% a S m a l lc lu s t e r sh a vel e s sth ano requ a lto1 0 0pub l i c a t ion s b S ign i f i c an tc lu s t e r sh a v e mo r eth an1 0 0pub l i c a t ion s - 41 T ab l e2. Th ee f f e c tono v e r a l lc i t a t ionin equ a l i t y ,I ( C ’) ,o fth ed i f f e r en c esinc i t a t ionimp a c tb e tw e enc lu s t e r s b e fo r eanda f t e rs t and a rdf i e ld no rm a l i z a t ion,andth eimp a c to fno rm a l i z a t iononth i se f f e c t No rm a l i z a t ionimp a c t= 1 0 0[ ID CC –IDC C*/ IDC C] B e fo r eno rm a l i z a t ion,1 0 0[ ID CC/I ( C ’) ] 2 2 . 5% - A f t e rno rm a l i z a t ion,1 0 0[ IDCC* /I ( C ’) ] 4 . 3% 8 4 . 3% R e su l t sf romC r e spoe ta l .( 2 0 1 4 )fo r2 1 9sub f i e ld s B e fo r eno rm a l i z a t ion,1 0 0[ ID CC/I ( C ’) ] 1 8 . 1% A f t e rno rm a l i z a t ion,1 0 0[ IDCC* /I ( C ’) ] 3 . 3% 8 7 . 3% R e su lt sf romL ie ta l .( 2 0 1 3 )fo r1 7 2sub f i e ld s B e fo r eno rm a l i z a t ion,1 0 0[ ID CC/I ( C ’) ] A v e r ag eo v e rs ixon ey e a rd a t a s e t s(S td .d e v . ) 1 3 . 1%(0 . 9 ) A f t e rno rm a l i z a t ion,1 0 0[ IDCC* /I ( C ’) ] A v e r ag eo v e rs ixon ey e a rd a t a s e t s(S td .d e v . ) 2 . 9 %( 0 . 4 ) 42 7 9 . 4% ( 4 . 3 ) 0 , 4 0 , 3 5 0 , 3 0 , 2 5 0 , 2 0 , 1 5 0 , 1 0 , 0 5 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 ip ir aw 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0 ip ino rm F igu r e1 .O v e r a l lc i t a t ionin equ a l i t ydu etod i f f e r en c e sinc i t a t ionpr a c t i c e s ,I ( π) ,a safun c t iono fπ.R e su l t s fo rth e[ 2 5 ,1 0 0 ]p e r c en t i l ein t e r v a l 43 T ab l e3. A .Emp t yc lu s t e r sinth es e t so fh ighimp a c ta r t i c l e sBandY,andp e r c en t ag eo fa r t i c l e sinth e in t e r s e c t ion sB∩X,andY∩X S e t so fh ighimp a c t a r t i c l e s Numb e ro f emp t yc lu s t e r s %o fa r t i c le sinX inth eemp t yc lu s t e r s %o fa r t i c l e sinth e in t e r s e c t ionw i thX B 1 , 0 7 8 2 . 6 7 6 5 . 8 Y 3 0 8 0 . 0 3 9 4 . 8 T ab l e3 .b .Emp t yc lu s t e r sinth es e t so fh ighimp a c ta r t i c l e sB ’andY ’,andp e r c en t ag eo fa r t i c l e sinth e in t e r s e c t ion sB ’∩X ’ andY ’, ’∩X ’ S e t so fh ighimp a c t a r t i c l e s Numb e ro f emp t yc lu s t e r s %o fa r t i c l e sin X inth eemp t yc lu s t e r s %o fa r t i c l e sinth e in t e r s e c t ionw i thX B ’ 1 1 7 1 . 3 7 6 6 . 6 Y ’ 3 0 8 0 . 0 0 9 4 . 9 - 44 2 2 0 0 2 0 0 0 Numb e ro fc lu s t e r s 1 8 0 0 1 6 0 0 1 4 0 0 1 2 0 0 1 0 0 0 8 0 0 6 0 0 4 0 0 2 0 0 0 < 2 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 % F igu r e2 .A .H igh imp a c ta r t i c l e sinth eo v e r a l lun -no rm a l i z edc i t a t iond i s t r ibu t ionC. H i s tog r amo fth e d i s t r ibu t iono v e r5 , 1 1 9c lu s t e r so fth ep e r c en t ag eth a tth e s ea r t i c l e sr ep r e s en tine a chc lu s t e r 7 0 0 Numb e ro fc lu s t e r s 6 0 0 5 0 0 4 0 0 3 0 0 2 0 0 1 0 0 0 > 6 6 . 0 6 . 5 7 . 0 7 . 5 8 . 0 8 . 5 9 . 0 9 . 51 0 . 01 0 . 51 1 . 01 1 . 51 2 . 01 2 . 51 3 . 01 3 . 51 4 . 01 4 . 51 5 . 0 % i s tog r amo fth e F igu r e2 .B .H igh imp a c ta r t i c l e sinth eo v e r a l lno rm a l i z edc it a t iond i s t r ibu t ionC*. H d i s t r ibu t iono v e r5 , 1 1 9c lu s t e r so fth ep e r c en t ag eth a tth e s ea r t i c l e sr ep r e s en tine a chc lu s t e r 45 6 0 0 Numb e ro fc lu s t e r s 5 0 0 4 0 0 3 0 0 2 0 0 1 0 0 0 > 6 6 . 0 6 . 5 7 . 0 7 . 5 8 . 0 8 . 5 9 . 0 9 . 51 0 . 01 0 . 51 1 . 01 1 . 51 2 . 01 2 . 51 3 . 01 3 . 51 4 . 01 4 . 51 5 . 0 % * . H i s tog r am o fth e F igu r e2 .C . H igh imp a c ta r t i c l e sinth eo v e r a l l no rm a l i z ed c i t a t ion d i s t r ibu t ion C' d i s t r ibu t iono v e r3 , 3 3 2c lu s t e r sw i th mor eth an2 5 0pub l i c a t ion so fth ep e r c en t a g eth a tth e s ea r t i c l e sr ep r e s en tin e a chc lu s t e r 46 T ab l e4 .A .Un i v e r s i t yre r ank inga c co rd ingtoth eTop1 0%ind i c a to rT a F romth e WoSc l a s s .s y s t emtog r anu l a r i t yl e v e l8 F i r s t1 0 0 un i v e r s i t i e s >5 0po s i t ion s 2 6–5 0 1 6–2 5 6–1 5 ≤ 5po s i t ion s Noch ang eb To t a l 0 7 1 3 3 6 4 4 1 0 0 N ex t4 0 0 un i v e r s i t i e s 8 1 1 0 7 7 4 8 1 5 7 4 0 0 To t a l 8 1 1 1 4 8 7 1 1 7 1 0 1 5 0 0 F romTitoT*i F i r s t1 0 0 R em a in ing4 0 0 un i v e r s i t i e s un i v e r s i t i e s 0 1 4 3 5 5 2 8 1 0 0 1 1 5 8 6 5 1 4 0 1 0 8 1 8 4 0 0 To t a l 1 1 5 9 6 9 1 7 5 1 6 0 2 6 5 0 0 T ab l e4 .B .Un i v e r s i t yd i f f e r en c e sinTiv a lu e s F romTitoT*i c F romth e WoSc l a s s .s y s t emtog r anu l a r i t yl e v e l8 N ex t4 0 0 F i r s t1 0 0un i v e rs i t i e s un i v e r s i t i e s >0 . 2 0 >0 . 1 0and≤0 . 2 >0 . 0 5and≤0 . 1 ≤0 . 0 5 To t a l 1 1 2 2 7 6 0 1 0 0 1 6 6 6 1 2 4 9 4 4 0 0 To t a l F i r s t1 0 0 un i v e r s i t i e s 1 7 7 8 1 5 1 2 5 4 5 0 0 0 3 2 6 7 1 1 0 0 aT ab l e6 .A inRu i zC a s t i l lo& W a l tm an( 2 0 1 5 ) bN o ta v a i l ab l e cT ab l e6 .B inRu i zC a s t i l lo& W a l tm an( 2 0 1 5 ) 47 N ex t4 0 0 un i v e r s i t i e s 0 8 4 9 3 4 3 4 0 0 To t a l 0 1 1 7 5 4 1 4 5 0 0 T ab l e5 .A .Un i v e r s i t yr e r ank ing sa c co rd ingtoth eAv e r ag eo fh igh imp a c tg ap sin d i c a to rA >5 0po s i t ion s 2 6–5 0 1 6–2 5 6–1 5 ≤ 5po s i t ion s Noch ang e To t a l F i r s t1 0 0 un i v e r s i t i e s R em a in ing4 0 0 un i v e r s i t i e s To t a l 0 0 1 2 1 7 0 8 1 0 0 1 6 1 2 1 2 6 2 2 0 3 5 4 0 0 1 6 1 3 1 4 7 2 9 0 4 3 5 0 0 F i r s t1 0 0 un i v e r s i t i e s R em a in ing4 0 0 un i v e r s i t i e s To t a l 5 5 7 3 1 7 1 0 0 3 3 8 1 5 7 2 0 2 4 0 0 8 9 5 1 8 8 2 0 9 5 0 0 T ab l e5 .B .Un i v e r s i t yd i f fe r en c e sinAiv a lu e s >0 . 2 0 >0 . 1 0and≤0 . 2 >0 . 0 5and≤0 . 1 ≤0 . 0 5 To t a l 48