The All Pairs, Tukey HSD test (also called Tukey-Kramer) protects the significance tests of all combinations of pairs, and the HSD intervals become greater than the Student’s t pairwise LSDs. Graphically, the comparison circles become larger and differences are less significant.
The q statistic is calculated as follows: q* = (1/sqrt(2)) * q where q is the required percentile of the studentized range distribution. See the description of the T statistic by Neter et al. (1990). See also Example of the All Pairs, Tukey HSD Test.