studentized range distribution Orlaith Burke A Dictionary of Statistics (2 rev ed.), OUP. ISBN-13: 9780199541454 http://www.oxfordreference.com/view/10.1093/acref/9780199541454.001.0001/acref-9780199541454-e-1588 Alejandra Gonzalez-Beltran Philippe Rocca-Serra The studentized range (q) distribution is a probability distribution used by the Tukey Honestly Significant Difference test. The distribution of the statistic [x̄(k)- x̄(1)]/(s/√n) where random samples of size n have been taken from k independent and identically distributed normal populations, with x̄(1) and x̄(k) being, respectively, the smallest and largest of the k sample means, and s2 being the pooled estimate of the common variance. This statistic is particularly used in multiple comparison tests. http://stat.ethz.ch/R-manual/R-patched/library/stats/html/Tukey.html http://www.stat.duke.edu/courses/Spring98/sta110c/qtable.html q distribution continuous probability distribution ready for release