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Date:         Sun, 8 Apr 2007 21:37:23 -0700
Reply-To:     David L Cassell <davidlcassell@MSN.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         David L Cassell <davidlcassell@MSN.COM>
Subject:      Re: Help with NLMIXED or GLIMMIX for multilevel GLMM
In-Reply-To:  <200704052110.l35J2EK3000491@mailgw.cc.uga.edu>
Content-Type: text/plain; format=flowed

qxu@UCDAVIS.EDU wrote: > >Dear all, > >I have a time allocation multinomial response data set in Anthropology. It >was a two year study on twenty families: from A to T; each family had >unequal number of individuals, for example, family A had individual A-1, A- >2, A-3, and family B had B-1, B-2. Each individual was observed by >anthropologists every six days at a random time during that day. Their >activities were recorded. For example, there are three activity codes: A- >doing agriculture work, L-Leisure, M-Marketing (there were more categories >in the original data, up to 26). The response will look like: >A-1: A A A M L ... (over two years) >A-2: A M M L M ... >. >. >. > >Now I want to fit a generalized linear mixed model for this response >against fixed effects, such as gender, age, with random effect for family >and person. (since each person has repeated observations over 2 years and >individuals were clustered in families.) >I attampted to fit the model by GLIMMIX using multinomial distribution and >glogit link, but convergence could not be reached. I could not figure >outhow to fit more than one level random effects in NLMIXED either. >Any suggestion is highly appreciated.

[1] How were the families selected? Isn't this really a survey sample? So isn't this something other than a multilevel GLMM? It looks to me (from way over here) like a simple cluster sample with lots of data over time. So it may be that you should be using PROC SURVEYLOGISTIC instead.

[2] If I'm right, then the random effects you perceive are simply survey sampling structure, and you have no random effects to handle in your model.

[3] Before I can get much further, I really need to know what your hypotheses are, and how you are testing them. It may be a royal pain to analyze as a survey sample model, or it may be a breeze. It depends on your hypothese and your data usage.

HTH, David -- David L. Cassell mathematical statistician Design Pathways 3115 NW Norwood Pl. Corvallis OR 97330

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