Dana uses the following parameters to determine that she needs asample size of 140 participants for her study that will compare themeans of two independent groups (t-test) using a one-tailedhypothesis:
           Effect size (d) = .5
           alpha = .05
           Power (1 - beta) = .90
Using the above information, answer each of the followingquestions.
a. If Dana keeps alpha and sample size the same, butdesires an effect size of .80, what will happen to power? Will itincrease or decrease? Explain.
b. If Dana keeps the desired effect size and sample size thesame, but reduces alpha to .025, what will happen topower? Will it increase or decrease? Explain.
c. If Dana keeps power and sample size the same, butincreases the desired effect size to .8, what will happen to alpha?Will it increase or decrease? Explain.
d. Dana decides she wants to increase the desired effect size to2.0 and increase the power to .99, but keeps alpha thesame. She does so to increase the likelihood that aneffect will be found, and to make sure her results demonstrate alarge enough effect. Also, when she conducts her a prioripower analysis to determine her sample size, she is excited to seethat she needs far fewer participants in her sample with thoseparameters (target n = 18). What, if any, are the problems withDana’s strategy?
