Hello Michael,
I can't see anything in your model that should cause randomise/permutation specific problems - you should be fine to start running randomise!
Many Regards
Matthew
>
> Hello,
> I'm implementing a 3 grp, heterogeneous slopes model in randomise, and I
> was wondering if there are any caveats or areas of caution when doing
> permutation testing with such a model?
>
> A graphic of my model is attached. It includes an EV (constant term)
> for each of the 3 groups (grp1,grp2,grp3), gender (as a nuisance
> variable), and then 3 group*variable regression terms
> (vgrp1,vgrp2,vgrp3). The contrasts that I'm interested in include the
> positive and negative "main" effect of slope (i.e., average of the 3
> separate group slopes), positive and negative contrasts on the
> difference of the slope of pair-wise groups, and the F-test looking for
> an overall slope difference between any of the 3 groups.
>
> I'm not using any exchangeability block labels file.
>
> My understanding from the web site description is that randomise
> automatically figures out the "nuisance" terms in the model from the
> contrast vectors. So, I think that running such a model in randomise is
> fine, but I suspect that this type of model doesn't get used in
> randomise all that often. Thus, I'd appreciate it if one of the
> randomise experts would give it their blessing!
>
> BTW: Does anyone have an electronic copy of the Freedman and Lane (1983)
> paper that describes the method randomise uses?
>
> thanks,
> -MH
>
>
> --
> Michael Harms, Ph.D.
> --------------------------------------------------------------------
> Conte Center for the Neuroscience of Mental Disorders
> Washington University School of Medicine
> Department of Psychiatry, Box 8134
> Renard Hospital, Room 6604 Tel: 314-747-6173
> 660 South Euclid Ave. Fax: 314-747-2182
> St. Louis, MO 63110 Email: [log in to unmask]
> --------------------------------------------------------------------
> <model1.png>
|