What is a one sample t test? The t test is a commonly used hypothesis test in statistics that allows us to compare the mean value of a group of sampled data with some hypothesized value, usually a ...

A t-test for population means compares the means between two populations. It is appropriate when the population standard deviations are unknown. This applet allows users to change the distributions of ...

Stein [4] has exhibited a double sampling procedure to test hypotheses concerning the mean of normal variables with power independent of the unknown variances. This procedure is here adapted to test ...