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Re: st: wsanova syntax


From   David Airey <david.airey@vanderbilt.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: wsanova syntax
Date   Wed, 4 Oct 2006 09:18:50 -0500

Christian Genova wrote:

Can someone kindly lend assistance on the wsanova syntax for repeated
measures. I'm still a novice with STATA so hope anyone can assist.

There are 2 repeated variables: id and control. ID is person belonging
to group "control". Tthe same persons in year 1 (id) belonging to group
(control) were analyzed in time 2.
I want to compare the scores in time 1 and 2, between time (scores in
time 1 compared with scores in time 2) and control in time 1 and 2
(whether there was signicant difference in scores of "control 1" at time
1 to scores at time 2, and within "control" in time 1 and 2 (whether
there was significant difference between scores of "control 1 and 2" in
time 1 compared to time 2).

time id control score
----------------------------------
1 1 1 5
1 2 1 6
1 3 1 5
1 1 2 3
1 2 2 4
2 1 1 7
2 2 1 8
2 3 1 5
2 1 2 2
2 2 2 10

I used: wsanova SCORE CONTROL, id(ID) between(TIME). Is this correct?


In the sample data, id==3 is not crossed with time and control. If time and control were both repeated variables, every level of time and control would be found in every id. Is this subset of the data, or is it the complete listing? You have just three subjects?

The standard Stata command (anova) handles repeated variables. No reason to use wsanova. See the Stata FAQs and the UCLA pages on Stata ANOVA and Stata xtmixed equivalents.

-Dave

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