To evaluate the effect of a treatment, a sample is obtained from a population with a mean of  = 20, and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be M = 21.3 with a variance of s2 = 9.

a. Assuming that the sample consists of n = 16 individuals, use a two-tailed hypothesis test with  = .05 to determine whether the treatment effect is significant and compute both Cohen’s d and r2 to measure effect size. Are the data sufficient to conclude that the treatment has a significant effect using a two-tailed test with  =.05?

b. Assuming that the sample consists of n = 36 individuals, repeat the test and compute both measures of effect size. c. Comparing your answers for parts a and b, how does the size of sample influence the outcome of a hypothesis test and measure of effect size?