In: Statistics and Probability
3. Let X1...Xn be N(μX,σ) and Y1...Yn be iid N(μy,σ) with the two samples X1...Xn, and Y1...Xn independent of each other. Assume that the common population SD σ is known but the two means are not. Consider testing the hypothesis null: μx = μy vs alternative: μx ≠ μy.
d. Assume σ=1 and n=20. How large must δ be for the size 0.01 test to have power at least 0.99?
e. Assume σ=1and δ=0.2. How large must n be for the size 0.01 test to have power at least 0.99?
Minitab output:
1-Sample Z Test
Testing mean = null (versus not = null)
Calculating power for mean = null + difference
Alpha = 0.01 Assumed standard deviation = 1.4142
Sample
Size Power Difference
20 0.99 1.55019
(e)
Minitab output:
Power and Sample Size
1-Sample Z Test
Testing mean = null (versus not = null)
Calculating power for mean = null + difference
Alpha = 0.01 Assumed standard deviation = 1.4142
Sample Target
Difference Size Power Actual Power
0.2 1202 0.99 0.990025