power.prop2: Approximates the power of a 2-group proportion test for...

In statpsych: Statistical Methods for Psychologists

Approximates the power of a 2-group proportion test for planned sample sizes

Description

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.

Usage

power.prop2(alpha, n1, n2, p1, p2, es)

Arguments

alpha	alpha level for hypothesis test
n1	planned sample size for group 1
n2	planned sample size for group 2
p1	planning value of proportion for group 1
p2	planning value of proportion for group 2
es	planning value of proportion difference

Value

Returns the approximate power of the test

Examples

power.prop2(.05, 60, 40, .5, .5, .2)

# Should return:
#     Power
# 0.4998959

statpsych documentation built on Sept. 11, 2024, 7:42 p.m.