In a fictional study, a pretest-posttest design was used to examine the influence of a television program on children's aggressiveness. The number of aggressive responses was measured during an observation period both before and after the television program.
(a) Determine if there is a difference in the number of aggressive behaviors in children after having viewed the television program, using a 95% confidence interval.
(b) Compute Cohen's d as a measure of effect size and interpret its meaning.