Bioequivalence and Bioavailability Forum

Hi Relaxation,

I read your post so many times now and I am somewhat confused.
What were you actually trying to prove or disprove?

Inclusion of a covariate one way or another makes an implicit assumption of a relationship that can be said to be linear between the covariate and the response (in the presence of the factors).

If the variance goes full Tasmanian devil on you when you include the covariate then perhaps this assumption is...well... of a nature that has the potential to cause some degree of debate. And then that is where the problem truly is.

In contrast to classical anovas where an additional factor will always decrease the unexplianed variance (or leave it unchanged, academically), the inclusion of a covariate is not necessarily having this effect.

Help me, please, I really wish to understand what this is all about.