Marrying Tukey's HSD and ANOVA results

Ben Bolker · 2011-11-19T00:57:20Z

Lara R. Appleby 04 writes: > I've done a standard two way ANOVA using glm on the dependent > variable "clutchsize" with the two factors "treatment" (which has 3 > levels called 1, 2, and 3) and "species" (which has two levels > called 1 and 2). Apparently there is no significant interaction > term. Then I did Tukey's HSD and found that there were significant > differences between species at only one of the three treatment > levels, treatment level 1. > > ##ANOVA RE

Ben Bolker

Fri, Nov 18, 2011 4:57 PM

Lara R. Appleby 04 <Lara.R.Appleby.04 at ...> writes:

I think you failed to tell R that `treatment' was a factor
(i.e. a categorical variable).  The Df in the output above
suggests that you are actually (accidentally) running a linear
regression on treatment number, rather than an ANOVA on
treatment.  The Df should be 2,1,2 for the design you
described above.

  That doesn't answer your other question, but it would
be better to sort out the more fundamental issue first.

Marrying Tukey's HSD and ANOVA results

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