Given two paired sets and of measured values, the paired -test determines if they differ from each other in
a significant way. Let

then define by

This statistic has Degrees of Freedom.

A table of Student's *t*-Distribution confidence interval can be used to
determine the significance level at which two distributions differ.

**References**

Goulden, C. H. *Methods of Statistical Analysis, 2nd ed.* New York: Wiley, pp. 50-55, 1956.

© 1996-9

1999-05-26