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

298 CHAPTER 9 | Introduction to the t Statistic
a standardized well-being questionnaire for which the
general population has an average score of μ = 40.
The well-being scores for this sample are as follows:
38, 37, 41, 35, 42, 40, 33, 33, 36, 38, 32, 39.
a. On the basis of this sample, is well-being for
frequent movers significantly different from wellbeing
in the general population? Use a two-tailed
test with α = .05.
b. Compute the estimated Cohen’s d to measure the
size of the difference.
c. Write a sentence showing how the outcome of
the hypothesis test and the measure of effect size
would appear in a research report.
23. Research examining the effects of preschool childcare
has found that children who spent time in day
care, especially high-quality day care, perform better
on math and language tests than children who stay
home with their mothers (Broberg, Wessels, Lamb, &
Hwang, 1997). In a typical study, a researcher obtains
a sample of n = 10 children who attended day care
before starting school. The children are given a standardized
math test for which the population mean is
μ = 50. The scores for the sample are as follows:
53, 57, 61, 49, 52, 56, 58, 62, 51, 56.
a. Is this sample sufficient to conclude that the
children with a history of preschool day care are
significantly different from the general population?
Use a two-tailed test with α = .01.
b. Compute Cohen’s d to measure the size of the
preschool effect.
c. Write a sentence showing how the outcome of
the hypothesis test and the measure of effect size
would appear in a research report.