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16. Functional foods are those containing nutritional supplements in addition to natural nutrients. Examples
include orange juice with calcium and eggs with omega3. Kolodinsky, et al. (2008) examined attitudes
toward functional foods for college students. For American students, the results indicated that females
had a more positive attitude toward functional foods and were more likely to purchase them compared to
males. In a similar study, a researcher asked students to rate their general attitude toward functional foods
on a 7point scale (higher score is more positive). The results are as follows:
Females Male
n = 8 n = 12
M = 4.69 M = 4.43
SS = 1.60 SS = 2.72
a. Do the data indicate a significant difference in attitude for males and females? Use a twotailed
test with = .05.
b. Compute r2, the amount of variance accounted for by the gender difference, to measure effect size.
c. Write a sentence demonstrating how the results of the hypothesis test and the measure of effect size
would appear in a research report.
18. Numerous studies have found that males report higher selfesteem than females, especially for adolescents (Kling, Hyde, Showers, & Buswell, 1999). Typical results show a mean selfesteem score of M = 39.0 with SS = 60.2 for a sample of n =10 male adolescents and a mean of M =35.4 with SS= 69.4 for a sample of n =10 female adolescents.
a. Do the results indicate that selfesteem is significantly higher for males? Use a onetailed test with = .01.
b. Use the data to make a 95% confidence interval estimate of the mean difference in selfesteem
between male and female adolescents.
c. Write a sentence demonstrating how the results from the hypothesis test and the confidence interval
would appear in a research report.
20. When people learn a new task, their performanceusually improves when they are tested the next day,
but only if they get at least 6 hours of sleep (Stickgold, Whidbee, Schirmer, Patel, & Hobson, 2000). The
following data demonstrate this phenomenon. The participants learned a visual discrimination task on one
day, and then were tested on the task the following day. Half of the participants were allowed to have at
least 6 hours of sleep and the other half were kept awake all night. Is there a significant difference
between the two conditions? Use a twotailed test with =.05.
Performance Scores
6 Hours of Sleep No Sleep
n =14 n =14
M =72 M =65
SS =932 SS =706
22. Downs and Abwender (2002) evaluated soccer players and swimmers to determine whether the routine blows to the head experienced by soccer players produced longterm neurological deficits. In the study,
neurological tests were administered to mature soccer players and swimmers and the results indicated
significant differences. In a similar study, a researcher obtained the following data.
Swimmers Soccer players
10 7
8 4
7 9
9 3
13 7
7
6
12
a. Are the neurological test scores significantly lower for the soccer players than for the swimmers in the
control group? Use a onetailed test with= .05.
b. Compute the value of r2 (percentage of variance accounted for) for these data.

Statistics 
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