Statistics for the Behavioral Sciences by Frederick J. Gravetter, Larry B. Wallnau ISBN 10: 1305504917 ISBN 13: 9781305504912

PROBLEMS 599
response, a sample of 120 college students is selected
and each student is given all three phones to use for
1 week. At the end of the week, the students must
identify which of the three designs they prefer. The
distribution of preference is as follows:
Design 1 Design 2 Design 3
54 38 28
Do the results indicate any significant preferences
among the three designs?
11. In Problem 10, a researcher asked college students to
evaluate three new cell phone designs. However, the
researcher suspects that college students may have
criteria that are different from those used by older
adults. To test this hypothesis, the researcher repeats
the study using a sample of n = 60 older adults in
addition to a sample of n = 60 students. The distribution
of preference is as follows:
Design 1 Design 2 Design 3
Student 27 20 13 60
Older Adult 21 34 5 60
48 54 18
Do the data indicate that the distribution of
preferences for older adults is significantly different
from the distribution for college students? Test
with α = .05.
12. Many businesses use some type of customer loyalty
program to encourage repeat customers. A common
example is the buy-ten-get-one-free punch card. Drèze
and Nunes (2006) examined a simple variation of this
program that appears to give customers a head start
on completing their cards. One group of customers at
a car wash was given a buy-eight-get-one-free card
and a second group was given a buy-ten-get-one-free
card that had already been punched twice. Although
both groups needed eight punches to earn a free wash,
the group with the two free punches appeared to be
closer to reaching their goal. A few months later, the
researchers recorded the number of customers who
had completed their cards and earned their free car
wash. The following data are similar to the results
obtained in the study. Do the data indicate a significant
difference between the two card programs. Test
with α = .05.
Buy-Eight-Get-
One-Free
Buy-Ten (with
2 Free Punches)
Completed
Not Completed
10 40 50
19 31 50
29 71
13. In a classic study, Loftus and Palmer (1974)
investigated the relationship between memory for
eyewitnesses and the questions they are asked.
In the study, participants watched a film of an
automobile accident and then were questioned about
the accident. One group was asked how fast the cars
were going when they “smashed into” each other.
A second group was asked about the speed when the
cars “hit” each other, and a third group was not asked
any question about the speed of the cars. A week
later, the participants returned to answer additional
questions about the accident, including whether they
recalled seeing any broken glass. Although there was
no broken glass in the film, several students claimed
to remember seeing it. The following table shows the
frequency distribution of responses for each group.
Verb Used
to Ask
About the
Speed
Response to the Question
Did You See Any Broken Glass?
Verb Used to Ask
About the Speed
Response About
Broken Glass
Yes
No
Smashed into 16 34
Hit 7 43
Control (Not Asked) 6 44
a. Does the proportion of participants who claim to
remember broken glass differ significantly from
group to group? Test with α = .05.
b. Compute Cramér’s V to measure the size of the
treatment effect.
c. Describe how the phrasing of the question influenced
the participants’ memories.
d. Write a sentence demonstrating how the outcome
of the hypothesis test and the measure of effect
size would be reported in a journal article.
14. In a study investigating freshman weight gain, the
researchers also looked at gender differences in
weight (Kasparek, Corwin, Valois, Sargent, & Morris,
2008). Using self-reported heights and weights,
they computed the Body Mass Index (BMI) for each