18. рорul. is administered to sample mean is found to be M = 49.2. Assuming that the sample standard deviation is 8, compute r and the estimated Cohen's d to a. measure the size of the treatment effect. b. Assuming that the sample standard deviation is 20, compute r2 and the estimated Cohen's d to measure the size of the treatment effect. Comparing your answers from parts a and b, how does the variability of the scores in the sample с. influence the measures of effect size? 21 19. A random sample is obtained from a population with a 45. After a treatment is administered to mean of u the individuals in the sample, the sample mean is M 49 with a standard deviation of s 12. a. Assuming that the sample consists of n = 9 scores, compute r2 and the estimated Cohen's d to measure the size of treatment effect. b. Assuming that the sample consists of n =16 scores, compute r2 and the estimated Cohen's d to measure the size of treatment effect. C. Comparing your answers from parts a and b, how does the number of scores in the sample influence the measures of effect size? 20. An example of the vertical-horizontal illusion is shown in the figure. Although the two lines are exactly the same length, the vertical line appears to be much longer. To examine the strength of this illusion, aro Onmnle in which both lines