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st: Randomized cross-over trial xtmixed og anova for repeated measurements
From
Christian Trolle <[email protected]>
To
"[email protected]" <[email protected]>
Subject
st: Randomized cross-over trial xtmixed og anova for repeated measurements
Date
Mon, 2 Dec 2013 07:57:48 +0000
Dear Statalist
I want to fit a ANOVA model for repeated measurements or an mixed linear model with xtmixed.
Comments on the design.
1. 7 patients seen at three visits randomized to three different interventions before each visit eg. fasting, exercise etc.
2. Main outcome is continuous, measured 4 times at each visit (0, 30 min, 60 min, 120 min).
3. The test should account for an unstructered covariance matrix
I have tried to fit a multivariate model like this:
egen VisitPatient = group(Visit Patient), label
xi: xtmixed Outcome bn.Time#bn.Visit || VisitPatient: i.Time, cov(un) technique(dfp)
I the use a likelihood ratio test to compare models.
The dataset could look like this
Visit Patient Outcome Time
0 1 y 1
0 1 y 2
0 1 y 3
0 1 y 4
0 2 y 1
0 2 y 2
0 2 y 3
0 2 y 4
0 3 y 1
0 3 y 2
0 3 y 3
0 3 y 4
0 4 y 1
0 4 y 2
0 4 y 3
0 4 y 4
0 5 y 1
0 5 y 2
0 5 y 3
0 5 y 4
0 6 y 1
0 6 y 2
0 6 y 3
0 6 y 4
0 7 y 1
0 7 y 2
0 7 y 3
0 7 y 4
1 1 y 1
1 1 y 2
1 1 y 3
1 1 y 4
1 2 y 1
1 2 y 2
1 2 y 3
1 2 y 4
1 3 y 1
1 3 y 2
1 3 y 3
1 3 y 4
1 4 y 1
1 4 y 2
1 4 y 3
1 4 y 4
1 5 y 1
1 5 y 2
1 5 y 3
1 5 y 4
1 6 y 1
1 6 y 2
1 6 y 3
1 6 y 4
1 7 y 1
1 7 y 2
1 7 y 3
1 7 y 4
2 1 y 1
2 1 y 2
2 1 y 3
2 1 y 4
2 2 y 1
2 2 y 2
2 2 y 3
2 2 y 4
2 3 y 1
2 3 y 2
2 3 y 3
2 3 y 4
2 4 y 1
2 4 y 2
2 4 y 3
2 4 y 4
2 5 y 1
2 5 y 2
2 5 y 3
2 5 y 4
2 6 y 1
2 6 y 2
2 6 y 3
2 6 y 4
2 7 y 1
2 7 y 2
2 7 y 3
2 7 y 4
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