(2) A Priori Power Analysis

Download the G*Power software provided, and then use the software to submit the following: a. Calculate the estimated sample size needed when given these factors:

• one-tailed t-test with two independent groups of equal size
• small effect size (see Piasta, S.B., & Justice, L.M., 2010)
• alpha =.05
• beta = .2 (Reminder: Power = 1 - beta)
• Assume that the result is a sample size beyond what you can obtain. Use the compromise function to compute alpha and beta for a sample half the size.
  • Indicate the resulting alpha and beta.
  • Analyze the result and decide if the study should be conducted with a smaller sample size. Explain your rationale.
  • In the context of Type I and Type II error.
  • Include a visual of the G* Power output matrix.

b. Calculate the estimated sample size needed to perform an ANOVA (fixed effects, omnibus, one-way) when given these factors:

• ANOVA (fixed effects, omnibus, one-way)
• small effect size
• alpha =.05
• beta = .2
• 3 groups
• Include a visual of the G* Power output matrix.