computes the deviate,
, associated with the lower tail probability of the distribution of the Studentized range statistic.
The externally Studentized range,, for a sample,
is defined as:
Where is an independent estimate of the standard error of the
's.
For a Studentized range statistic the probability integral, , for
degrees of freedom and
groups, can be written as:
where
For a given probability , the deviate
is found as the solution to the equation