Computes the sample size in each group required to estimate a ratio of
proportions with desired confidence interval precision in a 2-group design.
Set R = 1 for equal sample sizes.
Usage
size.ci.ratio.prop2(alpha, p1, p2, r, R)
Arguments
- alpha
alpha level for 1-alpha confidence
- p1
planning value of proportion for group 1
- p2
planning value of proportion for group 2
- r
desired upper to lower confidence interval endpoint ratio
- R
n2/n1 ratio
Value
Returns the required sample size for each group
Examples
size.ci.ratio.prop2(.05, .2, .1, 2, 1)
#> n1 n2
#> 416 416
# Should return:
# n1 n2
# 416 416
size.ci.ratio.prop2(.05, .2, .1, 2, .5)
#> n1 n2
#> 704 352
# Should return:
# n1 n2
# 704 352