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From | Johan van der Watt <jjvanderwatt@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: xtreg or xtmixed? |
Date | Mon, 19 Dec 2011 11:44:06 +0200 |
Hi I need to do longitudinal statistics on a panel data set of 150 individuals over 4 different time points. My dependent variable is the development of neuropathy (everyone is neuropathy free at baseline assessment), and a have numerous continuous independent variables/possible risk factors for development of neuropathy, such as CD4 count. A few of the continuous variables are not normally distributed, and I am able to normalize most of them by either logging or square rooting them. Further, looking at these variables over time, some of them also do not follow a linear pattern, i.e they peak at visit 2 or 3 then go down at visit 4. I have used the -xtreg- command with -mle-, using a continuous variable, such as CD4 count, Neuropathy, and Visit: xtreg cd4_ neuropathy visit, i(patientno2) mle but after reading online articles and bulletin boards, I have also tried the mixed effects model: xtmixed cd4_ neuropathy visit || patientno2:,mle As I am a stats amateur, is this what I am doing correct? Any other options? Thanks * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/