Van Aken and Asendorpf (1997) studied 139 German 12-year-olds. All of the children completed a general self-worth questionnaire and were interviewed about the supportiveness they experienced from their mothers, fathers, and classmates. The researchers then compared the self-worth of those with high and low levels of support of each type. The researchers reported that "lower general self-worth was found for children with a low supportive mother (t(137) = 4.52, p < .001, d = 0.78) and with a low supportive father (t(137) = 4.03, p < .001, d = 0.69). . . . A lower general self-worth was also found for children with only low supportive classmates (t(137) = 2.04, p 6 .05, d = 0.35)."
(a) Explain what these results mean to a person who has never had a course in statistics.
(b) Include a discussion of effect size and power. (When figuring power, you can assume that the two groups in each comparison had about equal sample sizes.)