The mean difference is a measure of statistical dispersion between means of two independent samples.

This app tests the hypothesis that the means, μ, of two samples are equal at some level of probablility, p. The relevant statistic is the Student's t-test for the appropriate probability and degrees of freedom, df.

The critical value of the t-test for 5% probability at 30 degrees of freedom is shown as t(0.05, 30).

There are three assumptions imbedded in this test. First, the samples must be randomly generated. Second, the samples must be independently sampled meaning that the inclusion of one subject does not influence the probability of selecting any other member of the population. Third, the population variances, or standard deviations as input into this app, of the two samples, A and B, are presumed to be equal.