Presenting results of a mixed model containing factors

Sarah Dryhurst <s.dryhurst at ...> writes:

Hi Ben,

Thank you for your reply!  I don't really want to calculate the main
effects as it doesn't make much biological sense (to me!).  I just
wasn't sure whether this was "required" in terms of statistical
reporting.  That interaction effect is what I am interested in
largely, as it's the combined effect of the different treatments that
is my focus.

I think it would still be worth reporting the main effects, as
their size puts the size of the interaction in perspective (e.g. I
would generally like to be able to judge the size of the interaction
*relative to* the main effects, not just its magnitude/t statistic/
p value ...

With regards to the lack of variance at the Block level, would you
recommend dropping this level here?  It doesn't seem to make too much
sense to keep it there...

Doesn't matter too much, since the results will be almost identical.
May be worth checking without, to double-check that the zero-variance
result hasn't thrown off the optimization, but I would personally
probably err on the side of reporting it (or say that it was in 
the original model but estimated as being effectively zero).