Gang Wrote:
-------------------------------------------------------
> There are a couple of possibilities for the
> discrepancies between 3dMVM and 3dLME.
>
> 1) If one quantitative is quite skewed among the
> subjects, that may have a large impact,
>
> 2) The way 3dLME counts the degrees of freedom is
> slightly different from 3dMVM, and the impact
> could be substantial if the number of subjects is
> on the lower end.
>
> Are all the quantitative variable between- or
> within-subject? With the former, you could still
> run 3dMVM with those covariates.

I have a similar question regarding 3dLME vs 3dMVM

In our setup, we are running a 2x4 repeated measures design. Both factors are within subjects. We've run both analyses using 3dMVM and 3dLME (with a random intercept). We get similar results in terms of location activated voxels, but 3dLME does have larger clusters than 3dMVM at the same p-value level. What is the cause of the difference in spatial extent? I've attached a picture showing the differences.

Also, should we ONLY use 3dLME if we have missing values. I thought 3dLME with a random intercept and 3dMVM should yield similar results. Does including a random intercept make that much of a difference?

When should we use 3dMVM vs 3dLME in the above example? Which result should we trust most?

Your help would greatly be appreciated.

Thanks.

Michael