Chapter 4 Worksheet
1. A study published in 2007 by Christopher Johnson, professor of music education
and music therapy at the University of Kansas, revealed that students in
elementary schools who took private music lessons scored around 20 percent
higher in math scores on standardized tests, compared to students who did not
take private music lessons.
1. What is the explanatory variable?
A. Music therapy
B. Whether a student took private music lessons
C. Math score on standardized test
D. Grade level
2. What is the response variable?
A. Music therapy
B. Whether a student took private music lessons
C. Math score on standardized test
D. Grade level
3. Which of the following could be a potential confounding variable?
A. Household income
B. Socioeconomic status
C. Whether the parents hired a math tutor
D. All of the above
2. The following table shows the responses from a sample of 680 people in the
General Social Survey to the question, “Do you sometimes drink more than you
think you should?”
Drink more than should?
Gender
Yes
No
Total
Male
151
177
328
Female
92
260
352
Total
243
437
680
1. What proportion of males responded that they drink more than they
should?
A. 151/243
B. 151/328
C. 243/680
D. 151/680
2. What proportion of those that responded they drink more than they should
are female?
A. 151/243
B. 92/243
C. 92/680
D. 352/680
3. Does there appear to be an association between gender and whether a
person responds that they drink more than they should?
A. Yes, since there are a different number of people of each gender.
B. Yes, since the percent that responded that they drink more than
they should differs from 50%.
C. Yes, since the proportion who responded they drink more than they
should differs between males and females.
D. No, there does not appear to be an association between these two
variables.
3. January 22, 2016, NPR news headline reads “Why Poverty May Be More
Relevant Than Race For Childhood Obesity.” The article states, “At first glance it
looked like childhood obesity was more common among African Americans or
Hispanics... When they accounted for poverty, though, the trend vanished.” The
study collected data on a random sample of K-12 students in Massachusetts.
Does this study design allow us to generalize results to the population of all
Massachusetts K-12 students?
A. Yes, since it is an observational study.
B. Yes, since it is a randomized experiment.
C. Yes, since the study used a random sample from the population.
D. No.
4. A study published in 2007 by Christopher Johnson, professor of music education
and music therapy at the University of Kansas, revealed that students in
elementary schools who took private music lessons scored around 20 percent
higher in math scores on standardized tests, compared to students who did not
take private music lessons. Is this a randomized experiment or an observational
study?
A. Randomized experiment, since researchers gave students standardized
tests.
B. Observational study, since whether the student took private music lessons
was not randomly assigned.
C. Observational study, since math scores were not randomly assigned.
D. Observational study, since this was not a random sample.
5. A randomized experiment was done by randomly assigning each participant
either to walk for half an hour three times a week or to sit quietly reading a book
for half an hour three times a week. At the end of a year the change in
participants' blood pressure over the year was measured, and the change was
compared for the two groups.
1. This is a randomized experiment rather than an observational study because:
a. Blood pressure was measured at the beginning and end of the
study.
b. The two groups were compared at the end of the study.
c. The participants were randomly assigned to either walk or read,
rather than choosing their own activity.
d. A random sample of participants was used.
2. If a statistically significant difference in blood pressure change at the end of a
year for the two activities was found, then:
A. It cannot be concluded that the difference in activity caused a difference in
the change in blood pressure because in the course of a year there are
lots of possible confounding variables.
B. Whether or not the difference was caused by the difference in activity
depends on what else the participants did during the year.
C. It cannot be concluded that the difference in activity caused a difference in
the change in blood pressure because it might be the opposite, that people
with high blood pressure were more likely to read a book than to walk.
D. It can be concluded that the difference in activity caused a difference in the
change in blood pressure because of the way the study was done.
6. Researchers randomly assigned patients with severe acne to one of two
treatments: the standard topical antibiotic (our control) or a new antibiotic taken
orally (the treatment). Six months later an evaluation of skin problems was made
by a doctor who did not know which medication subjects had been given. What is
the primary advantage of random assignment of the treatment?
A. It ensures that the study participants are representative of the larger
population.
B. It allows inference back to a population of patients with acne.
C. It allows the researchers to infer that any difference in outcome was due to
the treatments.
D. It ensures that the subject doesn't know which treatment they are getting
7. A research team conducted a randomized controlled trial to test a new medication
for reducing anxiety. Participants were randomly assigned to receive either the new
medication or a placebo. The study was double-blind, meaning neither the
participants nor the researchers knew who received the treatment or the placebo.
What is the primary purpose of this double-blind design?
A. To ensure the study results can be generalized to the larger population
B. To prevent bias in how the participants report their symptoms
C. To ensure that participants are randomly assigned to groups
D. To reduce the variability in the outcomes