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From |
April <aa713407@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: basic repeated measures question |

Date |
Tue, 17 Nov 2009 12:38:11 -0500 |

I have 3 questions regarding performing an ANOVA and 1 regarding doing a repeated measures logistic regression. I have tried to find examples for my questions but been unsuccessful. First, my data is setup up like this -- ID grp outcome time 1 1 15 1 1 1 16 2 2 2 12 1 2 2 20 2 3 3 20 1 3 3 12 2 4 4 20 1 4 4 22 2 1. I am interested in whether the change in the continuous outcome over time significantly differs by group. How would I setup this problem in an ANOVA? I would like to obatin the effect of time, group, and timeXgroup. I tried using repeated measures ANOVA code and this did not work (refer below) I wrote -- anova outcome id time grp, repeated(time) Received this error msg -- could not determine between-subject basic unit; use bseunit() option r(422); 2. If timeXgroup is significant, how do I perform simple effects analysis post hoc in order to understand how the outcome varied by each group over time and get a graph showing the trends 3. How would I include covariates in the model above essentially? 4. If my outcome was binary rather than continuous, I was interested in performing xtgee. How would you suggest setting up this code? I tried to set it up as below, but I did not get the OR for all groups (one of them was omitted). I believe I am specifying the model incorrectly. xtset id xi: xtgee outcome i.grp, family(binomial) link(logit) eform Any advice would be appreciated! Many 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/

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