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Date:   Mon, 12 Nov 2007 15:33:30 -0800
Reply-To:   Maurice Melancon <dmso12@GMAIL.COM>
Sender:   "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:   Maurice Melancon <dmso12@GMAIL.COM>
Subject:   Help with nested terms in PROC MIXED
In-Reply-To:   <87ba8bf70711121529i71921093o48712d75beeaf767@mail.gmail.com>
Content-Type:   text/plain; charset=ISO-8859-1

Hello, I'm new to mixed models, having run essentially all of my data for my dissertation using GLM. Normally, we'd have chosen 12 mice families (strains = 6 are cancer-prone, 6 are not) and would measure gene expression as a function of time, family, strain, and the interaction of time and strain using:

CLASS TIME STRAIN FAMILY; MODEL p53 = TIME STRAIN FAMILY(STRAIN) TIME* STRAIN; LSMEANS TIME*STRAIN #contrast statements, etc. using the nested term to 'block' for families. There is a different gene that was unanticipated, and we have re-classified families into different STRAINS which requires a random model. My limited understanding of code would be:

CLASS TIME STRAIN FAMILY; MODEL p53 = TIME STRAIN TIME* STRAIN; RANDOM FAMILY(STRAIN);

Does this model accomplish testing the nested term over the error and properly treat the random variable? Suggestions or reading would be appreciated.

Thanks,

Maurice


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