The Dunnett test is characterized by a particular minimum critical t-value (t), specificed for a given number of treatments (k) and degrees of freedom (nk-k, where n is the number of replicates, for a balanced experiment). If you hold n constant, how does t change as a function of k when k becomes large? Either a closed form equation (if there is one), or else a big table of Dunnett critical values on which I can do a regression would be fine. I’m looking for a bigger table than I can find through a google search or in a statistics textbook. I’ve tried using the standard table from statistics textbooks and it’s not detailed enough for me to really see the behavior at large k.

The basic issue here is I want to plot exactly how the critical value changes, for comparisons against a single control group, as you add more and more ‘test’ groups.