19. Research indicates that adolescent boys report higher levels of self-esteem than is reported by adolescent girls (Kling, Hyde, Showers, & Buswell, 1999). To examine this phenomenon a researcher obtains a sample of 40 adolescents, 20 boys and 20 girls, and administers a standardized measure of self-esteem to each participant. The boys produce a mean score of M  84 with SS  1940, and the girls produce M  73 with SS  1480.

a. Do these results indicate a significant difference in the level of self-esteem reported by adolescent girls and boys? Use a two-tailed test with  .01.

b. Compute Cohen’s d and r 2 to measure the size of the effect.