To test the effectiveness of a treatment, a sample of n = 25 people is selected from a normal population with a mean of µ = 60. After the treatment is administered to the individuals in the sample, the sample mean is found to be M = 55.
a. Compute Cohen's d measure effect size for both tests (σ = 20 and σ = 10).
b. Briefly describe how sample size influence the outcome of the hypothesis test. How does sample size influence measures of effect size?