Studentized Range Distribution (3 of 3)
Since the computed value of ts is always 1.414 times the value of t, the tests using ts and t are identical whenever there are only two means in an experiment. The difference between the t and the studentized t distributions occurs when there are more than two means. The figure below shows the critical value of t for the 0.05 level as a function of the number of means. This figure is based on an experiment with 24 degrees of freedom. Naturally, the more means, the higher the critical value of ts.
See also: Duncan, Newman Keuls, and Tukey HSD