This utility calculates the sample size required to detect a statistically
significant difference between two sample means with specified levels of confidence and
power, assuming equal sample sizes and equal variances.

Inputs are the assumed true values for the two means, the desired level of confidence
and the desired power for the detection of a significant difference and the estimated
combined variance. 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.