Sample size calculations
Sample size to detect a significant difference between 2 proportions
This utility calculates the sample size required to detect a statistically significant difference between two proportions with specified levels of confidence and power.
Inputs are the assumed true values for the two proportions, the desired level of confidence
and the desired power for the detection of a significant difference and the desired
ratio of sample sizes between the two groups. By default, calculations
assume that a two-tailed statistical test will be used, but a one-tailed test can also be
specified if preferred.
The program outputs the sample size required to detect the specified difference
with desired power and confidence, for a one-tailed or two-tailed statistical test,
as specified. Also output is a summary table of sample sizes for a range of
assumed prevalence values.