R/statpsych1.R
power.mean2.RdComputes the approximate power of a two-sample t-test for planned sample sizes. For a conservatively low power approximation, set the variance planning values to the largest values within their plausible ranges, and set the effect size to a minimally interesting value. The within-group variances can be unequal across groups and a Satterthwaite degree of freedom adjustment is used to improve the accuracy of the power approximation.
power.mean2(alpha, n1, n2, var1, var2, es)alpha level for hypothesis test
planned sample size for group 1
planned sample size for group 2
planning value of within-group variance for group 1
planning value of within-group variance for group 2
planning value of mean difference
Returns the approximate power of the test
power.mean2(.05, 25, 25, 5.0, 6.0, 2)
#> Power
#> [1,] 0.8398413
# Should return:
# Power
# [1,] 0.8398413