Hi Shannon, there is not a way in QDEC or with an FSGD file. You'll have to create a design matrix and feed that into mri_glmfit with the --X option. Let me know if you need any more assistance.
doug



On 9/10/12 5:43 PM, Shannon Kogachi wrote:
Hi Doug,
  I just wanted to double check on what you mean. I want to run statistical models without the interaction term. When I ran a test using DOSS and co-varying for sex, age, and ICV, I chose two discrete factors (study, sex), 1 covariate (age), and 1 nuisance factor (ICV). The results I got were the same as when I ran this in SAS but with the interaction term included:
model &yvar = study Sex study*sex age ICV

Is there a way in QDEC to run models without the interaction term (ex: study*sex)?

Thanks!

-Shannon

On Fri, Aug 24, 2012 at 1:05 PM, Douglas N Greve <greve@nmr.mgh.harvard.edu> wrote:
Hi Shannon, you can use the DOSS (different offset/same slope) instead
of DODS
doug

On 08/20/2012 03:47 PM, Shannon Kogachi wrote:
> Hi,
>   I was wondering if there is a way to run statistical tests, such as
> a 2-way ANCOVA, on QDEC but without the interaction effect. I ran a
> 2-way ANCOVA for thickness measures for a longitudinal study, and no
> interaction effect was found. Therefore, I would like to run the same
> test but without the interaction effect and see if there are other
> group effects. Please let me know if there is a way to do this in QDEC
> or any other statistical programs in FreeSurfer. Thank you!
>
>
> -Shannon
>
>
>
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