1. State the critical (tabled) value of t that would be used to reject the null hypothesis of equality of population means, for an independent groups t-test under each of the following conditions:

1. H1: μ1 ≠ μ2; n1 = 20, n2 = 20; α = .05 40-2=38 40=2.02 for t. 30=2.04 for +/-2.02 Two Tails
2. H1: μ1 > μ2; n1 = 30, n2 = 30; α = .01 One Tail >2.39
3. H1: μ1 ≠ μ2; n1 = 10, n2 = 10; α = .01 +/-2.88
4. H1: μ1 > μ2; n1 = 60, n2 = 60; α = .05 one tail >1.66
5. H1: μ1 ≠ μ2; n1 = 15, n2 = 10; α = .01 +/-2.81

2. For a post hoc power analysis, d = .60, α = .05 for a two-tailed t test, and the number of people in each of two groups = 30, the power of the t-test is approximately 0.61.

1. What was the risk of a Type II error?
2. For the same effect size (.60), approximately what n per group would be needed to achieve power = .80?