Computes the sample size in each group (assuming equal sample sizes) required to estimate a linear contrast of proportions with desired confidence interval precision in a between-subjects design. Set the proportion planning values to .5 for a conservatively large sample size.

size.ci.lc.prop.bs(alpha, p, w, v)

Arguments

alpha

alpha level for 1-alpha confidence

p

vector of proportion planning values

w

desired confidence interval width

v

vector of between-subjects contrast coefficients

Value

Returns the required sample size per group

Examples

p <- c(.25, .30, .50, .50)
v <- c(.5, .5, -.5, -.5)
size.ci.lc.prop.bs(.05, p, .2, v)
#>      Sample size per group
#> [1,]                    87

# Should return:
#      Sample size per group
# [1,]                    87