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From | "Airey, David C" <david.airey@Vanderbilt.Edu> |
To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
Subject | re: st: repeated (sic) longitudinal analysis |
Date | Wed, 8 Sep 2010 15:12:10 -0500 |
. I think -xtgee- only allows one level of repeated measures data, not more. If you have multilevel data, you need to use mixed models, such as -xtmixed-. -Dave > Dear all, > I am analysing the following study : > - healthy subjects are eating a meal ad libitum and the quantity of food (number of forks for example) is recorded every minute : energy, glucids, lipids and proteins > - the meal is repeated 3 times in 2-4 weeks : once fasted (meal 0) and twice not fasted (meals 1 & 2). > Usually I use xtgee to do longitudinal analyses when subjects are different, something like : > xtset id_subject minute > xi: xtgee kcal i.meal, family(gaussian) link(identity) corr(exchangeable) > > But this time the same subject eats the three meals and I want to know if the three curves are different in their shape (besides the AUC, slopes...). > Do you have any idea how to include in the GEE model the fact that it is the same subject who is re-recorded to take into account this variability ? > It sounds to me like clusters but I didn't find how to put it in the GEE model. I had also a look at gllamm but I am not familiar with it. > Thanks for your help. Best regards, > Hubert * * 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/