power.mean.ps {statpsych}

Approximates the power of a paired-samples t-test for a planned sample size

Description

Computes the approximate power of a paired-samples t-test for a planned sample size. For a conservatively low power approximation, set the variance planning values to the largest values within their plausible ranges, set the correlation planning value to the smallest value within its plausible range, and set the effect size to a minimally interesting value. The variances of the two measurements can be unequal.

Usage

power.mean.ps(alpha, n, var1, var2, es, cor)

Arguments

alpha

alpha level for hypothesis test

n

planned sample size

var1

planning value of measurement 1 variance

var2

planning value of measurement 2 variance

es

planning value of mean difference

cor

planning value of correlation between measurements

Value

Returns the approximate power of the test

Examples

power.mean.ps(.05, 20, 10.0, 12.0, 2, .7)

# Should return:
#     Power
# 0.9074354