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 a = .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.