size.ci.lc.mean.bs: Sample size for a between-subjects mean linear contrast...

In statpsych: Statistical Methods for Psychologists

Sample size for a between-subjects mean linear contrast confidence interval

Description

Computes the sample size in each group (assuming equal sample sizes) required to estimate a linear contrast of population means with desired confidence interval precision in a between-subjects design. Set the variance planning value to the largest value within a plausible range for a conservatively large sample size.

Usage

size.ci.lc.mean.bs(alpha, var, w, v)

Arguments

alpha	alpha level for 1-alpha confidence
var	planning value of average within-group variance
w	desired confidence interval width
v	vector of between-subjects contrast coefficients

Value

Returns the required sample size for each group

Examples

v <- c(.5, .5, -1)
size.ci.lc.mean.bs(.05, 5.62, 2.0, v)

# Should return:
# Sample size per group
#                    34
 

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