Date:         Fri, 1 Aug 2003 10:53:28 -0500
Reply-To:     Paul Thompson <paul@WUBIOS.WUSTL.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Paul Thompson <paul@WUBIOS.WUSTL.EDU>
Organization: Washington University in St. Louis
Subject:      Re: Trouble with CONTRAST in GLM
Content-Type: text/plain; charset=us-ascii; format=flowed

Yer in luck.  I have written a macro to properly devise contrasts in
complex cases, like yours.  To get a copy, send me an email.

Patrick wrote:
> Greetings, all.
>
> This may be a bit basic compared to most of what goes by this
> board, but I'm stuck.
>
> I'm running a 2x2x2x2 ANCOVA in GLM, and want to contrast two cells
> at the 3-way interaction level.  I set it up in what I thought was
> the correct manner, but I'm getting 'CONTRAST is not estimable.'
>
> It may be that some of the cell sizes are too small (the smaller
> ones are in the 10-12 range), but if anyone can spot something I'm
> doing wrong, I'd appreciate it.  I've never really gotten the hang
> of CONTRAST.
>
> The code:
>
> proc glm data=ni;
>   class interv rprob aprob cohort male black site;
>   model read2=interv|rprob|aprob|cohort male black site iq;
>   contrast 'Two cells' interv*rprob*aprob 1 0 0 0 0 -1 0 0 /e;
> run;
>
> The log and output are at http://www.duke.edu/
> ~malone/contrastouput.html .
>
> Appreciate any help,
> Pat