Oh and I forgot part 2, my contrasts. Main effects are easy (1 1 -1 -1 
or 1 -1 1 -)

but for interaction, since it put the interaction terms in the model, 
I think it would be an F contrast of  [0 0 0 0 1 -1 1 -1]
Confirmation of this would make me feel a lot better, I've been as 
confident in f contrasts as I'd like as I so rarely make use of them!

best,
Colin

Quoting [log in to unmask]:

> Dear all,
>
> I'm sure this has been addressed before but my list search didn't 
> run up a clear answer (a reflection on my poor search skills than 
> the clarity of past answers, I am sure).
>
> I am running a repeated measures type ANOVA design, with a group 
> (between subject) by time/session (pre-post, within subject) design. 
> After some consideration, flexible factorial seemed the best way to 
> go.
>
> I set for main effects of time and session, as well as the 
> interaction. My design matrix is attached.
>
> I set independence for no for 'time', but not for group, while I 
> left variance unequal (after all we expect changes over time, so I 
> expect possible unequal variance).
>
> First I wanted to check if this seems OK.
>
> Second, I wanted to check if maybe we should model subject as an 
> additional factor? It seems to maybe be already embedded implicitly 
> in the flexible factorial. If I add this factor, but don't specify a 
> main effect, it doesn't appear in the design matrix, which I found a 
> bit surprising (it should still be modeled even if we don't contrast 
> it, for the effects on the Beta estimation).
>
> Thanks a lot,
> Colin