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

600 CHAPTER 17 | The Chi-Square Statistic: Tests for Goodness of Fit and Independence
student. Based on the BMI scores, the students were
classified as either desirable weight or overweight.
When the students were further classified by gender,
the researchers found results similar to the frequencies
in the following table.
Desirable
Weight
Overweight
Males 74 46
Females 62 18
a. Do the data indicate that the proportion of overweight
men is significantly different from the proportion
of overweight women? Test with α = .05.
b. Compute the phi-coefficient to measure the
strength of the relationship.
c. Write a sentence demonstrating how the outcome
of the hypothesis test and the measure of effect
size would be reported in a journal article.
15. Research results suggest that IQ scores for boys
are more variable than IQ scores for girls (Arden &
Plomin, 2006). A typical study looking at 10-year-old
children classifies participants by gender and by low,
average, or high IQ. Following are hypothetical data
representing the research results. Do the data indicate
a significant difference between the frequency distributions
for males and females? Test at the .05 level of
significance and describe the difference.
IQ
Low Average High
Boys 18 42 20 80
Girls 12 54 14 80
n = 160
17. In a study similar to one conducted by Fallon and
Rozin (1985), a psychologist prepared a set of silhouettes
showing different female body shapes ranging
from somewhat thin to somewhat heavy and asked a
group of women to indicate which body figure they
thought men would consider the most attractive. Then
a group of men were shown the same set of profiles
and asked which image they considered the most
attractive. The following hypothetical data show the
number of individuals who selected each of the four
body image profiles.
a. Do the data indicate a significant difference
between the actual preferences for the men and the
preferences predicted by the women? Test at the
.05 level of significance.
b. Compute the phi-coefficient to measure the
strength of the relationship.
Somewhat
Thin
Body Image Profiles
Slightly
Thin
Slightly
Heavy
Somewhat
Heavy
Women 29 25 18 8 80
Men 11 15 22 12 60
40 40 40 20
18. A recent study indicates that people tend to select video
game avatars with characteristics similar to those of
their creators (Bélisle & Bodur, 2010). Participants
who had created avatars for a virtual community game
completed a questionnaire about their personalities. An
independent group of viewers examined the avatars and
recorded their impressions of the avatars. One personality
characteristic considered was introverted/extroverted.
The following frequency distribution of personalities for
participants and the avatars they created.
16. Gender differences in dream content are well documented
(see Winget & Kramer, 1979). Suppose a
researcher studies aggression content in the dreams of
men and women. Each participant reports his or her
most recent dream. Then each dream is judged by a
panel of experts to have low, medium, or high aggression
content. The observed frequencies are shown in the
following matrix:
Introverted
Avatar
Extroverted
Avatar
Participant Personality
Introverted Extroverted
22 23 45
16 39 55
38 62
Gender
Aggression Content
Low Medium High
Female 18 4 2
Male 4 17 15
Is there a relationship between gender and the aggression
content of dreams? Test with α = .01.
a. Is there a significant relationship between the personalities
of the participants and the personalities
of their avatars? Test with α = .05.
b. Compute the phi-coefficient to measure the size of
the effect.
19. Research indicates that people who volunteer to participate
in research studies tend to have higher intelligence
than nonvolunteers. To test this phenomenon,