Name: Arnold Jerry Solano
Subject: Biostatistics
1. A teacher wishes to know whether the males in his/her class have more conservative
attitudes than the females. A questionnaire is distributed assessing attitudes and the males
and the females are compared. Is this an example of descriptive or inferential statistics?
It is a descriptive statistic due to the data just gives a little summary and a simple description
of the sample (class).
2. A cognitive psychologist is interested in comparing two ways of presenting stimuli on
subsequent memory. Twelve subjects are presented with each method and a memory test is
given. What would be the roles of descriptive and inferential statistics in the analysis of these
data?
In this specific case, inferential statistics will be used to draw (boxplot, histograms, etc) the
conclusion of this study. One the other hand, descriptive statistics (mean, median, mode, etc)
could be used in order to be able to describe the data collected.
3. If you are told that you scored in the 80th percentile, from just this information would you
know exactly what that means and how it was calculated? Explain.
Well, the data does not tell me the exactly score that I got, moreover; it means that my score is
under the 80% scores in the sample (to be more specific 80%). So, as the percentiles shows a
percentage of the total population, it is possible to calculate following the next equation.
𝑅 = (𝑃/100) ∗ (𝑁 + 1)
R = Rank
P= Percentile
N= number of the sample
4. A study is conducted to determine whether people learn better with spaced or massed
practice. Subjects volunteer from an introductory psychology class. At the beginning of the
semester 12 subjects volunteer and are assigned to the massed-practice condition. At the end
of the semester 12 subjects volunteer and are assigned to the spaced-practice condition. This
experiment involves two kinds of non-random sampling: (1) Subjects are not randomly
sampled from some specified population and (2) Subjects are not randomly assigned to
conditions.
Which of the problems relates to the generality of the results?
(1) It is related to the generality of the results, then; conclusion from the generality of the
result is skewed.
Which of the problems relates to the validity of the results?
(2) So, the problems are related to the validity of the results.
Which problem is more serious?
The problem (2) is more serious if we compare with the problem 1 due to it invalidates the
experimental findings. Also, problem (1) will not permit generalizing the results.
5. Give an example of an independent and a dependent variable.
An experiment to determine how far people can see into the infrared part of the spectrum.
The wavelength of light is the independent variable, on the other hand; observed light is the
dependent variable.
6. Categorize the following variables as being qualitative or quantitative:
Rating of the quality of a movie on a 7-point scale: Quantitative
Age: Quantitative
Country you were born in: Qualitative
Favorite Color: Qualitative
Time to respond to a question: Quantitative
7. Specify the level of measurement used for the items in Question 6.
Rating of the quality of a movie on a 7-point scale: Ordinal scale
Age: Ratio scale
Country you were born in: Nominal scale
Favorite Color: Nominal scales
Time to respond to a question: Ratio scale
8. Which of the following are linear transformations?
Converting from meters to kilometers
Squaring each side to find the area
Converting from ounces to pounds
Taking the square root of each person's height
Multiplying all numbers by 2 and then adding 5
Converting temperature from Fahrenheit to Centigrade
9. The formula for finding each student's test grade (g) from his or her raw score (s) on a test
is as follows: g = 16 + 3s
Is this a linear transformation?
Yes, it is because it converts from one scale to another and multiplying by 3
If a student got a raw score of 20, what is his test grade?
g=16 + 3(20) = 16 + 60 = 76
10. For the numbers 1, 2, 4, 16, compute the following:
4
∑ 𝑥𝑖 = 𝑥1 + 𝑥2 + 𝑥3 + 𝑥4
𝑖=1
= 1 + 2 + 4 + 16 = 23
4
∑ 𝑥𝑖2 += 𝑥12 + 𝑥22 + 𝑥32 + 𝑥42
𝑖=1
12 + 22 + 42 + 162 = 277
4
2
(∑ 𝑥𝑖 ) = (23)2 = 529
𝑖=1
11. Which of the frequency polygons has a large positive skew? Which has a large negative
skew?
(A) positive skew
(B) and (c) negative skew
12. What is more likely to have a skewed distribution: time to solve an anagram problem
(where the letters of a word or phrase are rearranged into another word or phrase like "dear"
and "read" or "funeral" and "real fun") or scores on a vocabulary test?
It is more likely to have a skewed distribution in scores on a vocabulary test due to it is easier
than solving an anagram problem which leads to having distributions positive skew and negative
skew in contrast solving an anagram problem will have different distributions.
Questions from Case Studies:
13. (AM#1) Which variables are the participant variables? (They act as independent variables
in this study.)
Sports
Gender
Both variables are qualitative (ordinal) variables because in the dataset people are separated
with numbers as 1 and 2.
14. (AM#2) What are the dependent variables?
Anger in
Anger out
Control in
Control out
Expression
15. (AM#3) Is Anger-Out a quantitative or qualitative variable?
Quantitative (discrete) because there are just integer numbers in the data set
16. (TR#1) What is the independent variable in this study?
Conditions (charismatic and punitive) which is a nominal variable
17. (AT#1) What is the independent variable of this experiment? How many levels does it
have?
the doses of the medicine which is a quantitative variable.
There were 4 levels of measurement which are 0, 15, 30, 60 mg/km
18. (AT#2) What is the dependent variable? On what scale (nominal, ordinal, interval, ratio)
was it measured?
The dependent variable is the response time more than 4 seconds to press the button in order
to get a star. So, it can be a radio scale because it is possible to get 0 time as a response.
0
