Hi there,
I need assistance with interpreting the outcome of my pairwise comparisons from my datasets. I've been running a glmer mixed models and selecting the best model using the AIC criteria. Please view my post on stack for all the code:
https://stackoverflow.com/questions/45369820/pairwise-comparisons-of-contrasts-from-lsmeans-p-value-adjustment
I read that for mixed models where the distribution is not normal, Tukey's HSD isn't advised. This would appear to be true given how highly significant the interaction between Pre and Adult is. When I put the Tukey's HSD adjustment in, I lose nearly all the significant pairwise comparisons.
So for the time being I've specified the adjustment as NULL (I've looked at SIDAK adjustment too but still lose these signficant pariwise comparisons). Looking at my data visually, the data appear to match the stats when the NULL adjustment is applied.
I would like some advice as to whether or not I should report these contrasts and if so how I report them, considering there is no post-hoc adjustment. ie. do I say: "all pariwise comparisons were computed from the contrasts between factors using lsmeans package".
Any help would be greatly appreciated. I hope I'm going about this the right way!
Thanks!
Dave
Hi David.
You You could use planned contrasts in anova, with the following code:
if your variable have 4 levels (e. control, group 1, group 2 and group 3)
ControlvsOther
RVL on your Cross Validated post is Russell Lenth. You can't get a better advisor on multiple comparisons with ls means than him.
I think saying something like "all pairwise comparisons were computed from the contrasts between factors using lsmeans package" is reasonable. But your reader will assume that you did some kind of p-value adjustment, so you really should indicate "No p-value adjustments were made to account for multiple comparisons." This may raise the eyebrows of reviewers.
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