New tables for multiple comparisions with control.

A method is presented for choosing an additive constant c when transforming data x to y = log(x + c). The method preserves Type I error probability and power in ANOVA under the assumption that the x + c* for some c* are log-normally distributed. The method has advantages similar to those of rank transformations-namely, it is easy to use and is resistant to extreme observations. Since the special case c →∞ corresponds in