Approximates the power of a 2-group proportion test for planned sample sizes
Source:R/statpsych3.R
power.prop2.Rd
Computes the approximate power for a test of equal population proportions in a 2-group design for the planned sample sizes. This function requires planning values for both proportions. Set the proportion planning values to .5 for a conservatively low power estimate. The planning value for the proportion difference could be set to the difference of the two proportion planning values or it could be set to a minimally interesting effect size.