statpsych (version 2.0.0)

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

Description

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

For more details, see Section 3.25 of Bonett (2021, Volume 1)

Usage

size.test.lc.mean.bs(alpha, pow, var, es, v)

Value

Returns the required sample size for each group

Arguments

alpha

alpha level for hypothesis test

pow

desired power

var

planning value of average within-group variance

es

planning value of linear contrast of means

v

vector of between-subjects contrast coefficients

References

Bonett2021statpsych

Examples

v <- c(1/4, 1/4, 1/4, 1/4, -1)
size.test.lc.mean.bs(.05, .90, 1, .5, v)

# Should return:
# Sample size per group
#                    53

v <- c(1, -1, -1, 1)
size.test.lc.mean.bs(.05, .90, 27.5, 5, v)

# Should return:
# Sample size per group
#                    47