Page 1 of 1 PSY2061 Research Methods Lab © 2013 South University Steroid Usage, Grip Strength, Aggression, and Happiness Study Steroid Usage Grip Strength Aggression Happiness Investigator 3 12 7 5 1 11 49 19 7 1 23 54 30 3 1 15 19 21 6 1 19 64 24 7 2 4 20 5 10 2 19 57 19 5 2 13 21 18 11 2 24 78 36 14 3 6 15 32 11 3 14 17 4 9 3 29 87 26 5 4 2 12 8 5 4 17 74 22 6 4 4 35 6 7 4 Steroid Usage: The number entered reflects the number of weeks on steroids. Grip Strength: The number registered on a hand meter. The larger the number, the stronger the person; the scale cannot go higher than 100. Aggression: The number obtained on the McGuthry Aggression Inventory. The higher the number, the more aggression; the scale goes from 5 to 30. Happiness: The number obtained on the Happiness Scale. The higher the number, the happier the person is; the scale goes from 0 to 15. Investigator: The number assigned to the person who assessed the participant. Chapter 3, Section 2, Exercise 068ad Bisphenol A in Your Soup Cans Bisphenol A (BPA) is in the lining of most canned goods, and recent studies have shown a positive association between BPA exposure and behavior and health problems. How much does canned soup consumption increase urinary BPA concentration? That was the question addressed in a recent study1 in which consumption of canned soup over five days was associated with a more than 1000% increase in urinary BPA. In the study, 75 participants ate either canned soup or fresh soup for lunch for five days. On the fifth day, urinary BPA levels were measured. After a two-day break, the participants switched groups and repeated the process. The difference in BPA levels between the two treatments was measured for each participant. The study reports that a 95% confidence interval for the difference in means (canned minus fresh) is 19.6 to 25.5 μg/L. 1Carwile J., Ye X., Zhou X., Calafat A., and Michels K., "Canned Soup Consumption and Urinary Bisphenol A: A Randomized Crossover Trial," Journal of the American Medical Association, 2011; 306(20): 2218–2220. (a) Is this a randomized comparative experiment or a matched pairs experiment? Randomized comparative experiment Matched pairs experiment SHOW HINT LINK TO TEXT (d) If the study had included 500 participants instead of 75, would you expect the confidence interval to be wider or narrower? Wider Narrower Click if you would like to Show Work for this question: Open Show Work SHOW HINT LINK TO TEXT ter 3, Section 2, Exercise 061acd Have You Ever Been Arrested? According to a recent study of 7335 young people in the US, 30% had been arrested1 for a crime other than a traffic violation by the age of 23. Crimes included such things as vandalism, underage drinking, drunken driving, shoplifting, and drug possession. 1From a study in USA Today, quoted in The Week, 2012; 11: 547–548..

1. Page 1 of 1
PSY2061 Research Methods Lab
© 2013 South University
Steroid Usage, Grip Strength, Aggression, and Happiness Study
Steroid Usage Grip Strength Aggression Happiness Investigator
3 12 7 5 1
11 49 19 7 1
23 54 30 3 1
15 19 21 6 1
19 64 24 7 2
4 20 5 10 2
19 57 19 5 2
13 21 18 11 2
24 78 36 14 3
6 15 32 11 3

2. 14 17 4 9 3
29 87 26 5 4
2 12 8 5 4
17 74 22 6 4
4 35 6 7 4
Steroid Usage: The number entered reflects the number of
weeks on steroids.
Grip Strength: The number registered on a hand meter. The
larger the number, the stronger the
person; the scale cannot go higher than 100.
Aggression: The number obtained on the McGuthry Aggression
Inventory. The higher the
number, the more aggression; the scale goes from 5 to 30.
Happiness: The number obtained on the Happiness Scale. The
higher the number, the happier
the person is; the scale goes from 0 to 15.
Investigator: The number assigned to the person who assessed
the participant.

3. Chapter 3, Section 2, Exercise 068ad
Bisphenol A in Your Soup Cans
Bisphenol A (BPA) is in the lining of most canned goods, and
recent studies have shown a positive association between BPA
exposure and behavior and health problems. How much does
canned soup consumption increase urinary BPA concentration?
That was the question addressed in a recent study1 in which
consumption of canned soup over five days was associated with
a more than 1000% increase in urinary BPA. In the
study, 75 participants ate either canned soup or fresh soup for
lunch for five days. On the fifth day, urinary BPA levels were
measured. After a two-day break, the participants switched

4. groups and repeated the process. The difference in BPA levels
between the two treatments was measured for each participant.
The study reports that a 95% confidence interval for the
difference in means (canned minus fresh) is 19.6 to 25.5 μg/L.
1Carwile J., Ye X., Zhou X., Calafat A., and Michels K.,
"Canned Soup Consumption and Urinary Bisphenol A: A
Randomized Crossover Trial," Journal of the American Medical
Association, 2011; 306(20): 2218–2220.
(a) Is this a randomized comparative experiment or a matched
pairs experiment?
Randomized comparative experiment
Matched pairs experiment
SHOW HINT
LINK TO TEXT

5. (d) If the study had included 500 participants instead of 75,
would you expect the confidence interval to
be wider or narrower?
Wider
Narrower
Click if you would like to Show Work for this question:
Open Show Work
SHOW HINT
LINK TO TEXT

6. ter 3, Section 2, Exercise 061acd
Have You Ever Been Arrested?
According to a recent study of 7335 young people in the
US, 30% had been arrested1 for a crime other than a traffic
violation by the age of 23. Crimes included such things as
vandalism, underage drinking, drunken driving, shoplifting, and
drug possession.
1From a study in USA Today, quoted in The Week, 2012; 11:
547–548.
(a) Is the 30% a parameter or a statistic?
Parameter
Statistic

7. SHOW HINT
LINK TO TEXT
(b) The margin of error for the population proportion
estimate, p, is 0.01. Use this information to give a range of
plausible values for the parameter.
The plausible values for the proportion p range from to .
SHOW HINT
LINK TO TEXT
(c) Given the margin of error in part (b), if we asked all young

8. people in the US if they have ever been arrested, is it likely that
the actual proportion is less than 25%?
Yes
No
Click if you would like to Show Work for this question:
Open Show Work
SHOW HINT
LINK TO TEXT
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9. Chapter 3, Section 1, Exercise 031
Graduate Programs in Statistics!
One of the many wonderful things about studying statistics is
that graduate programs in statistics often pay their graduate
students, which means that many graduate students in statistics
are able to attend graduate school tuition free with an
assistantship or fellowship. In 2009, there were 82 US statistics
or biostatistics doctoral programs for which enrollment data
were available.1 The dataset StatisticsPhD lists all these
schools together with the total enrollment of full-time graduate
students in each program in 2009.
Click here for the dataset associated with this question.
Click here to access StatKey.
1Full list of the 82 Group IV departments was obtained at
http://www.ams.org/profession/data/annual-survey/group_iv.
Data on enrollment obtained primarily from Assistantships and
Graduate Fellowships in the Mathematical Sciences, 2009,
American Mathematical Society. The list does not include
combined departments of mathematics and statistics and does
not include departments that did not reply to the AMS survey.

10. (a) A random sample of 10 of the 82 enrollment values is given
in the table below. Give the notation for the sample mean.
University
Department
Enrollment
Case Western Reserve University
Statistics
11
University of South Carolina
Biostatistics
45
Harvard University
Statistics
67
University of California - Riverside
Statistics
54
Medical University of South Carolina
Biostatistics
46
University of Nebraska
Statistics
44
New York University
Statistics
6
University of Minnesota
Biostatistics
48
University of Iowa

11. Biostatistics
35
Cornell University
Statistics
78
SHOW HINT
LINK TO TEXT
(b) Compute the sample mean.
Enter the exact answer.
Sample mean=
exact number, no tolerance
SHOW HINT
LINK TO TEXT

12. (c) Another random sample of 10 of the 82 enrollment values is
given in the table below. Give the notation for this sample
mean.
University
Department
Enrollment
University of Wisconsin
Statistics
116
Baylor University
Statistics
26
Yale University
Statistics
36
Iowa State University
Statistics
145
Boston University
Biostatistics
39
University of Nebraska
Statistics
44
Columbia University

13. Statistics
196
University of California - Los Angeles
Biostatistics
60
University of California - Davis
Statistics
34
Virginia Commonwealth University
Statistics
15
SHOW HINT
LINK TO TEXT
(d) Compute the sample mean.
Enter the exact answer.
Sample mean =
exact number, no tolerance

14. SHOW HINT
LINK TO TEXT
(e) Give the notation for the mean enrollment value for the
entire population of these 82 graduate programs.
SHOW HINT
LINK TO TEXT

15. (f) Find the mean enrollment value for the entire population of
these 82 graduate programs.
Round your answer to two decimal places.
Mean=
the absolute tolerance is +/-0.1
SHOW HINT
LINK TO TEXT
(g) Consider the sampling distribution if we calculate many
sample means taking samples of size n=10 from this population
of enrollment values. What shape will it have?
Skewed to the left
Skewed to the right
Symmetric and bell-shaped

16. Symmetric but not bell-shaped
None of these
SHOW HINT
LINK TO TEXT
(h) Where will the sampling distribution be centered?
Round your answer to two decimal places.
Center=
the absolute tolerance is +/-0.5
Click if you would like to Show Work for this question:
Open Show Work
SHOW HINT
LINK TO TEXT

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Chapter 3, Section 2, Exercise 067bd
Playing Video Games
A new study provides some evidence that playing action video
games strengthens a person's ability to translate sensory
information quickly into accurate decisions. Researchers
had 23 male volunteers with an average age of 20 look at
moving arrays on a computer screen and indicate the direction
in which the dots were moving.1 Half of the volunteers
(11 men) reported playing action video games at least five times
a week for the previous year, while the other 12 reported no

18. video game playing in the previous year. The response time and
the accuracy score were both measured. A 95% confidence
interval for the mean response time for game players minus the
mean response time for non-players is -1.8 to -1.2 seconds,
while a 95% confidence interval for mean accuracy score for
game players minus mean accuracy score for non-players is -
4.2 to +5.8.
1Green, et al., "Improved probabilistic inference as a general
learning mechanism with action video games," Current Biology,
2010; 20(September 14): 1.
(a) Is it likely that game players and non-game players are
basically the same in response time? If not, which group is
faster (with a smaller response time)?
Likely to be basically the same
Not likely to be the same, and game players are faster
Not likely to be the same, and non-game players are faster

19. SHOW HINT
LINK TO TEXT
(b) Is it likely that game players and non-game players are
basically the same in accuracy? If not, which group is more
accurate?
Likely to be basically the same
Not likely to be the same, and game players are more accurate
Not likely to be the same, and non-game players are more
accurate
Click if you would like to Show Work for this question:
Open Show Work
SHOW HINT
LINK TO TEXT

20. Chapter 3, Section 2, Exercise 066
Males vs Females and One True Love
In a study, a random sample of 2625 US adults were asked
whether they agree or disagree that there is "only one true love
for each person." The response and gender of the participants is
shown in Table 1.
Male
Female
Total
Agree
372
363
735
Disagree
807
1005

21. 1812
Don't know
34
44
78
Total
1213
1412
2625
Table 1 Is there only one true love for each person?
(a) Use the information in the table to construct
a 95% confidence interval for the difference in the proportion
who agree, between males and females, using the fact that the
standard error for the difference is 0.018.
Round your answers to three decimal places.
The 95% confidence interval is to .
(b) Is it plausible that there is no difference between males and
females in the proportion who agree that each person has only
one true love?
Click if you would like to Show Work for this question:
Open Show Work
SHOW HINT
LINK TO TEXT

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edicting Election Results
Throughout the US presidential election of 2012, polls gave
regular updates on the sample proportion supporting each
candidate and the margin of error for the estimates. This attempt
to predict the outcome of an election is a common use of polls.

23. In each case below, the proportion of voters who intend to vote
for each candidate is given as well as a margin of error for the
estimates. Indicate whether we can be relatively confident that
candidate A would win if the election were held at the time of
the poll. (Assume the candidate who gets more than 50% of the
vote wins.)
(a)
Candidate A: 54%
Candidate B: 46%
Margin of error: ±5%
Confident A would win
Not confident in the outcome
SHOW HINT
LINK TO TEXT

24. (b)
Candidate A: 52%
Candidate B: 48%
Margin of error: ±1%
Confident A would win
Not confident in the outcome
SHOW HINT
LINK TO TEXT
(c)

25. Candidate A: 53%
Candidate B: 47%
Margin of error: ±2%
Confident A would win
Not confident in the outcome
SHOW HINT
LINK TO TEXT
(d)
Candidate A: 58%
Candidate B: 42%
Margin of error: ±10%
Confident A would win

26. Not confident in the outcome
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hapter 3, Section 1, Exercise 037
Gender in the Rock and Roll Hall of Fame
From its founding through 2012, the Rock and Roll Hall of
Fame has inducted 303 groups or individuals. Forty-seven of the
inductees have been female or have included female
members.1 The full dataset is available in RockandRoll.
Click here for the dataset associated with this question.

27. Click here to access StatKey.
1Rock and Roll Hall of Fame website: rockhall.com/inductees.
(a) Give the correct notation for the proportion of inductees
who have been performers?
SHOW HINT
LINK TO TEXT
(b) What proportion of inductees have been female or have
included female members?
Round your answer to three decimal places.

28. Proportion=
the absolute tolerance is +/-0.001
SHOW HINT
LINK TO TEXT
(c) If we took many samples of size 50 from the population of
all inductees and recorded the proportion female or with female
members for each sample, what shape do we expect the
distribution of sample proportions to have? Where do we expect
it to be centered?
Round your answer for the center to three decimal places.
Shape
:
Center
:
the absolute tolerance is +/-0.001
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Open Show Work

29. SHOW HINT
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hapter 3, Section 2, Exercise 064
Number of Text Messages a Day
A random sample of n=755 US cell phone users age 18 and
older in May 2011 found that the average number of text

30. messages sent or received per day is 41.5 messages,1 with
standard error about 6.1.
1Smith, A., "Americans and Text Messaging," Pew Research
Center, http://www.pewinternet.org/Reports/2011/Cell-Phone-
Texting-2011/Main-Report/How-Americans-Use-Text-
Messaging.aspx, accessed September 19, 2011.
(a) Use the information from the sample to give the best
estimate of the population parameter.
x¯=
exact number, no tolerance
SHOW HINT
LINK TO TEXT

31. (b) Find a 95% confidence interval for the mean number of text
messages.
The 95% confidence interval is to .
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