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re: st: Anova repeated measures


From   "Airey, David C" <david.airey@Vanderbilt.Edu>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   re: st: Anova repeated measures
Date   Sat, 10 Apr 2010 20:19:10 -0500

.

With repeated measures ANOVA the time of collection is crossed with subject. You have subjects with different time points. Other methods like xtmixed allow different time of measures per subject, but your data set of 3 subjects is too small for this method. Maybe a randomization approach? I'm assuming you want to conclude a downward trend across 3 subjects is significant? Always start your analysis with a plot!

reshape long t vas, i(id) j(time)
gr tw connected vas t, connect(L)

Is it possible to collect more subject data?

-Dave


> My dataset:
> 
> id t1  t2  t3  vas1  vas2  vas3   group
> 1  23  45  67  8     8     7     1
> 2  21  57  77  5     3     3     2
> 3  47  58  60  4     1     .     3
> 
> t1 is minutes after t0 where vas1 is measured
> t2 is minutes after t0 where vas2 is measured
> t3 is minutes after t0 where vas3 is measured
> 
> First I would like to stratify the VAS-values into 3 equally sized
> time groups from t1 to t3. How?
> 
> Second, I think I need to use anova repeated measures to document any
> difference in VAS between the groups. Is that right and how?
> 
> Thank you in advance!

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