T-distributions are most likely used to compare two process means. It is a hypothesis test of means.
Video on How to Create a 1 Sample T Test in MiniTab
- http://www.cliffsnotes.com/math/statistics/univariate-inferential-tests/one-sample-t-test (One sample T test)
- http://www.cliffsnotes.com/math/statistics/univariate-inferential-tests/two-sample-t-test-for-comparing-two-means (Two sample T test for comparing two means / DF for separate s: the smaller of n 1– 1 and n 2– 1 DF for pooled s: df = n 1+ n 2– 2)