Sample size for a test of a within-subjects mean linear contrast

Computes the sample size required to test a linear contrast of population means with desired power in a within-subjects design. Set the average variance planning value to the largest value within a plausible range for a conservatively large sample size. Set the average correlation planning value to the smallest value within a plausible range for a conservatively large sample size.

Usage

size.test.lc.mean.ws(alpha, pow, var, es, cor, q)

Arguments

alpha: alpha level for hypothesis test
pow: desired power
var: planning value of average variance of measurements
es: planning value of linear contrast of means
cor: planning value of average correlation between measurements
q: vector of with-subjects contrast coefficients

Value

Returns the required sample size

Examples

q <- c(.5, .5, -.5, -.5)
size.test.lc.mean.ws(.05, .90, 50.7, 2, .8, q)
#>  Sample size
#>           29

# Should return:
# Sample size
#          29