size.test.lc.prop.bs: Sample size for a test of between-subjects proportion linear contrast
Description
Computes the sample size in each group (assuming equal sample sizes) required
to test a linear contrast of population proportions with desired power in a
between-subjects design. The planning value for the effect size (linear
contrast of proportions) could be set equal to the linear contrast of
proportion planning values or it could be set equal to a minimally interesting
effect size. For a conservatively large sample size, set the proportion planning
values to .5 and set the effect size to a minimally interesting value.