Inferential Statistics Practice Exam & Answers with Explanations
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Course
Inferential Statistics (6461PI006Y)
Institution
Universiteit Leiden (UL)
I made this practice exam after my actual exam in 2022. The end of the document contains helpful explanations for each correct answer option.
There are 30 multiple-choice questions, just like in the actual exam.
DISCLAIMER: The majority of these questions were made by me (a student), only for practice
purposes. I cannot guarantee that these questions are completely representative of what the actual
exam will be like. I made it after taking the exam in January 2022. Also, one of the questions was not
written by me, but it was discussed in the lectures.
There are 30 multiple choice questions. For each question, out of the 4 alternatives only one is
correct. Complete it in 2 hours if you want to have the actual exam’s experience.
The answers and explanations are in a separate document.
The questions begin on the next page.
Good luck :)
,QUESTION 1. In a study of differences in depression score before and after cognitive behavioral
therapy, it was hypothesized that H0: µ2- µ1 = 0, Ha: µ2- µ1 < 0. They found that 𝑥̅ = 0.9 with p =
.072. What is your statistical and substantive conclusion?
a) reject H0, the therapy significantly helps in decreasing depression
b) reject H0, the therapy has no significant effect on depression
c) accept H0, the therapy significantly helps in decreasing depression
d) do not reject H0, the therapy has no significant effect on depression
QUESTION 2. A researcher is interested whether there is a significant difference in the IQs of people
with blue eyes and brown eyes. In this sample, what is the probability a person has a high IQ given
that they have blue eyes?
a) 0.20 blue eyes brown eyes total
b) 0.35 High IQ 23 29 52
c) 0.42 Low IQ 42 21 63
d) 0.45 total 65 50 115
QUESTION 3. A teacher is planning to repaint a classroom. She asks her students (n = 40) what color
she should choose (red, blue, green, yellow). The frequencies are: red =4, blue =18, green =7 and
yellow=11. Which test should be performed here?
a) independent samples t-test
b) chi-square test for homogeneity
c) chi-square test for independence
d) chi-square test for goodness-of-fit
QUESTION 4. In the Netherlands, the average time spent studying for Dutch students is 4.8 hours per
day with a standard deviation of 1.54. A researcher hypothesizes that international students study
more. She obtains a sample of 40 international students with the following statistics: x = 5.13 s =
1.1. What is the value of the test statistic?
a) 1.355
b) 1.897
c) -1.897
d) -1.3553
QUESTION 5. In a study, they want to find out whether people who watch TV have more radical
views than people who don’t watch TV. They measure 200 participants (120 TV-watchers and 80 non-
TV-watchers). The results are shown in the table below.
TV watchers non-TV watchers total
radical views 51 19 70
no radical views 69 61 130
total 120 80 200
I. Which test should be used here?
II. What is the expected value for TV watchers with no radical views?
a) I. Chi-square test for homogeneity; II. 78
b) I. Chi-square test for independence; II. 78
c) I. Chi-square test for independence; II. 42
d) I. Chi-square test for homogeneity; II. 42
, QUESTION 6. In a famous scientific article, the following results are reported: t(67) = 8.753, p <
0.001, CI95 = [8.345;9.478]. What conclusion can be drawn from this?
a) the researcher was 95% confident that the results are significant between [8.345;9.478]
b) The interval of [8.345;9.478] is the area in which the value of the population mean is
significant in 95% of the cases
c) The interval of [8.345;9.478] is the area in which the true value of the population mean lies is
in 95% of the cases
d) The interval of [8.345;9.478] is the area in which the true value of the sample mean lies is in
95% of the cases
QUESTION 7. In which case would a nonparametric test be used?
a) level of measurement is numerical and n is very large
b) n is very small, regardless of level of measurement
c) level of measurement is ordinal
d) level of measurement is numerical and the sample is normally distributed
QUESTION 8. Which statement about the p value is correct?
a) It is the probability of rejecting the null hypothesis.
b) It is the probability of finding the obtained test statistic or a less extreme one given that the
null hypothesis is true
c) It is the probability of finding the obtained test statistic or a more extreme one given that the
null hypothesis is true
d) It is the probability of finding the obtained test statistic or a more extreme one given that the
null hypothesis is false
QUESTION 9. Which statistical element expresses the difference between 2 groups in standard
deviation units?
a) power
b) confidence interval
c) absolute effect size
d) relative effect size
QUESTION 10. A population has the following statistics: µ = 7.1. We take a sample of 31 from it for
which we obtain the following statistics: x = 4.2 s = 1.9. What is the value of the standard error of the
mean?
a) 𝑆𝐸 ̅ = 0.4
b) 𝑆𝐸 ̅ = 4.2
c) 𝑆𝐸 ̅ = 2.9
d) 𝑆𝐸 ̅ = 0.3
QUESTION 11. In a population, for a specific aspect, every value between 1 and 10 is equally likely.
What happens when we obtain a sample of it?
a) the bigger sample we obtain, the closer it will be to a normal distribution
b) the smaller sample we obtain, the closer it will be to a normal distribution
c) the bigger sample we obtain, the closer it will be to a unipolar distribution
d) the smaller sample we obtain, the closer it will be to a unipolar distribution
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