qdist(alpha,K,v)

qdist returns a value from the studentized range or q-distribution.

This function returns the table lookup value of the Studentized Range or q-distribution for Tukey HSD Post-Hoc means comparison. It has a maximum of 20 groups (K). If more groups are used K=20 is used for the table lookup.

Input:
alpha = Confidence level
K = Number of groups
v = Degrees of freedom

Example:
q=qdist(0.10,5,15)
ans =
3.8280

q=qdist(0.05,5,15)
ans =
4.3670

q=qdist(0.01,5,15)
ans =
5.5560

Data for the tables was taken from
http://cse.niaes.affrc.go.jp/miwa/probcalc/s-range/