6th (In)formative Capsule
Multiple selection lists: “Check-all that apply” versus “forced-choice”
In any type of questionnaire it is usually necessary to ask the respondent to choose several
options in a set of available alternatives. A typical format for this kind of questions is the
“check-all-that-apply”; it is used when we have a list – generally a long one – of items in which
we might want to know all the answers that apply for each respondent. For example, from a
list of n brands we would like to know which ones the respondent knows and which ones have
been bought during the last 12 months, or which alternatives the respondent would
recommend. In a similar way, from a list of n activities, we could ask which options the
respondent practise at least once a week, or the activities he/she has done at least once in
his/her life, etc.
The “check-all-that-apply” questions are usually presented like this:
Q1- Please, tick all the brands you have bought during the last 12 months:
Brand 1
Brand 2
…
Brand n
In online questionnaires, the element that allows respondents to tick each item (named as
“input type”) is normally a “checkbox”, which is a squared box that can be selected and
unselected easily by clicking on it. Using this element to choose more than one option from a
list is a standard of web communication.
An alternative way to ask the same question is to list each item and request the respondent to
answer “yes” or “no” for each of them. This kind of question is known as “forced-choice
format” because the respondent must indicate whether this applies or not. It is usually
presented as following:
Q1alternative- Please, for each of the following brands indicate whether you have bought or
not these brand products in the last 12 months:
Brand 1
Brand 2
…
Brand n
Yes
○
○
○
○
No
○
○
○
○
In order to have an enquiry with this format in an online questionnaire it is normally used pairs
of “radio-buttons”; one for the option “yes” and the other for the option “no”. The “radio1/4
6th (In)formative Capsule
buttons” have a circular shape and only allow selecting one element of the group. So, when
one “radio-button” is picked, the rest become automatically unavailable (in this case, if we pick
“yes” we won’t be able to pick “no” as it will be blocked and vice versa). This does not mean
that the respondent will not be able to change the chosen answer.
In face-to-face surveys (CAPI) or phone surveys (CATI), the second alternative “forced-choice”
is more used as it would be very difficult for the responder to hear a long list of items and
remember all the options that apply in order to number them at the end. It is much easier to
answer “yes” or “no” as the respondent listen to each item, before moving on to assess the
next one. However, on paper or online surveys where the respondent can see all the items
written on the paper or on the screen this memory problem does not exist. That is why a lot of
surveys use the format “check-all-that-apply”.
Often, both formats are used as if they were equivalent or interchangeable. Many researchers
when they migrate surveys from paper to CAPI/CATI or from CAPI/CATI to online, they only
transform questions from one format to the other, without worrying about the consequences
that this change can have in the results.
Otherwise, the differences that exist between the data produced by both formats using the
alternative “check-all-that-apply”, is that if the respondents do not make enough effort to
answer properly the question (reading and evaluating conveniently each of the given options),
we could encourage them to choose less items than the ones that really apply (known by
“weak satisficing”). In this way, a respondent that selects 3 options from a list of 10, may think
that he/she has done his/her duty and that it is not necessary to keep making efforts in
reading and evaluating all of the other options.
On the other hand, it has been proven that people has tendency to answer yes1
(“acquiescence” or “yes-saying”) more often, so when we ask a respondent to indicate “yes” or
“no” in a “forced-choice” format, we can cause respondents to choose more times “yes” than
what in fact corresponds to reality.
To make sure whether those phenomena occur in practice, Smyth et al (2006) compared 16
experiments in 2 online surveys and 1 on paper (2002-2003) in the United States of America.
After analyzing the results, they found that the 2 formats do not act in an equivalent way: the
respondents choose more items whit the “yes/no” format, rather than when using a “checkall-that-apply” format. The Smyth et al (2006) shows that the problem comes from the
“satisficing” experimented in the “check-all-that-apply”, and not from the tendency of answer
“yes” in the format “yes/no”. Therefore, they conclude that the format “forced-choice” is
preferable, or in other words, it gets results that are closer to reality.
Since both, the tendency of saying “yes” and the “weak satisficing”, can vary between
countries, in Netquest – within the scope of the research project of R2online.org – we have
carried out experiments in different countries of the Ibero-America region: Spain, Mexico and
1
As seen in the 5th (In)formative Capsule:
The use of balanced questions reduces the impact of the tendency of respondents to answer "yes"
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Colombia. In table 1, we can observe a list of 7 items asking about political activities (e.g.:
whether the respondent has ever signed a petition to a government, whether the respondent
has ever contact a politician…). Here we can see an average of how many times the
respondents said yes with the format “yes/no” and with the format “check-all-that-apply”, in
each of the 3 countries.
Table 1: Average of items selected out of the 7 items of the matrix
Mexico
Yes/N
CATA
o
Average number of
items to those who
said “yes”
1.88
1.53
Colombia
Spain
Yes/No
CATA
Yes/No
CATA
2.06
1.70
2.10
1.60
Note: CATA = check-all-that-apply
The results are similar to those obtained by Smyth et al (2006): there are more political
actions reported when using format “yes/no” than when using the “check-all-that-apply”
format.
It is clear that the format “check-all-that-apply” collects more mentions, but ¿which
information is more real? To know which of these 2 formats is preferable, we have performed
a test of external validity, considering the correlations between the total number of items that
a respondent affirms to have done and a variable with which theoretically should find a high
correlation; in this case, we use a question about the interest that the respondent has towards
politics (B1- To what extend would you say you are interested in politics? A lot, quite a lot, not
much, not at all). Supposedly, the greater interest in politics the higher number of activities
related to politics should be observed. Thus, the format that gets this correlation higher is the
one we should consider as preferable.
Table 2: Correlation between total number of selected items and the politics’ interest
Mexico
Colombia
Spain
Yes/N
CATA
Yes/No CATA Yes/No CATA
o
Correlation
-.4175 -.3456
-.3739 -.3727 -.3663 -.3067
The correlations are similar in Colombia, but in Mexico and Spain are higher in the “yes/no”
format”, which means that this format is more preferable than the “check-all-that-apply” one.
Therefore, the experiments carried out in the Ibero-America region agree with the ones found
by Smyth et al (2006) in USA.
In conclusion, in different countries seem that respondents do not make the maximum effort
to answer properly when the “check-all-that-apply” format is used, as they choose less items
than the ones that really apply. Clearly, both formats are not equivalent and so they are not
interchangeable.
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Bibliographic references:
Jolene D. Smyth, Don A. Dillman, Leah Melani Christian, and Michael J. Stern (2006).
Comparing Check-All and Forced-Choice Question Formats in Web Surveys. Public Opinion
Quarterly (Spring 2006) 70(1): 66-77 doi:10.1093/poq/nfj007
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