This function performs Tukey's single degree of freedom test for interaction in an unreplicated two-factor design
Tukey1df(data)
input - this is a data frame with three variables, the first variable is a numeric response and next two variables are factors. There should be \(ab\) lines in the data frame where \(a\) is the number of levels of the first factor, and \(b\) is the number of levels of the second factor.
John Lawson