Research examining the effects of preschool child- care has found that children who spent time in day care, especially high-quality day care, perform better on math and language tests than children...

Research examining the effects of preschool child-
care 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 stan-
dardized 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.