15.41 Consider an experiment with treatment factors A and B, with factor A having four levels and factor B having three levels. The results of the experiment are summarized in the following analysis of variance table.

Compute the mean squares and test the null hypotheses of no effect from either treatment and no interaction effect.

Source of Variation Sum of Squares Degrees of Freedom Treatment A groups 90 4 Treatment B groups 82 2 Interaction 26 8 Error 260 60 Total 458 74