Power and Sample Size

2-Sample t Test

Testing mean 1 = mean 2 (versus >)
Calculating power for mean 1 = mean 2 + difference
α = 0.2
Assumed standard deviation = 20

            Sample  Target
Difference    Size   Power  Actual Power
         5      91     0.8      0.800402

The sample size is for each group.

Power and Sample Size

2-Sample t Test

Testing mean 1 = mean 2 (versus >)
Calculating power for mean 1 = mean 2 + difference
α = 0.05
Assumed standard deviation = 20


            Sample  Target
Difference    Size   Power  Actual Power
         5     275    0.90      0.900260
         5     347    0.95      0.950006
         5     506    0.99      0.990070

 The sample size is for each group.