Dear Statalisters,

I am trying to implement a mixed-effet repeated measures model that was described by Hamlett, Ryan, Serrano-Trespalacios & Wolfinger in their paper entitled "" (Journal of Air and Waste Management Association, 2003. 53:4 442-50). The paper appears to be freely accessible from the publisher.

The model is described mathematically, where repeated measures are taken on individuals using two different, correlated, measurements. They then give a worked example of implementing the model in SAS. From reading the article, I know there should be a random-effect for the measurement type with an unstructured covariance matrix, and then residual errors of each replicate to be nested within each individual. I can't seem to wrap my head around the appropriate syntax for -mixed-.

I've provided a data example below. My best guess at the syntax would be:

Code:
mixed response ibn.vtype, nocons || person : vtype, cov(un) || _all : , nocons resid(ind, by(vtype) t(repl))
These data are for the linked data example and are attributable to Bland and Altman.

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input byte(personid vtype replicate) double(response)
1 1 1 6.68
1 2 1 3.97
1 1 2 6.53
1 2 2 4.12
1 1 3 6.43
1 2 3 4.09
1 1 4 6.33
1 2 4 3.97
2 1 1 6.85
2 2 1 5.27
2 1 2 7.06
2 2 2 5.37
2 1 3 7.13
2 2 3 5.41
2 1 4 7.17
2 2 4 5.44
3 1 1  7.4
3 2 1 5.67
3 1 2 7.42
3 2 2 3.64
3 1 3 7.41
3 2 3 4.32
3 1 4 7.37
3 2 4 4.73
3 1 5 7.34
3 2 5 4.96
3 1 6 7.35
3 2 6 5.04
3 1 7 7.28
3 2 7 5.22
3 1 8  7.3
3 2 8 4.82
3 1 9 7.34
3 2 9 5.07
4 1 1 7.36
4 2 1 5.67
4 1 2 7.33
4 2 2  5.1
4 1 3 7.29
4 2 3 5.53
4 1 4  7.3
4 2 4 4.75
4 1 5 7.35
4 2 5 5.51
5 1 1 7.35
5 2 1 4.28
5 1 2  7.3
5 2 2 4.44
5 1 3  7.3
5 2 3 4.32
5 1 4 7.37
5 2 4 3.23
5 1 5 7.27
5 2 5 4.46
5 1 6 7.28
5 2 6 4.72
5 1 7 7.32
5 2 7 4.75
5 1 8 7.32
5 2 8 4.99
6 1 1 7.38
6 2 1 4.78
6 1 2  7.3
6 2 2 4.73
6 1 3 7.29
6 2 3 5.12
6 1 4 7.33
6 2 4 4.93
6 1 5 7.31
6 2 5 5.03
6 1 6 7.33
6 2 6 4.93
7 1 1 6.86
7 2 1 6.85
7 1 2 6.94
7 2 2 6.44
7 1 3 6.92
7 2 3 6.52
8 1 1 7.19
8 2 1 5.28
8 1 2 7.29
8 2 2 4.56
8 1 3 7.21
8 2 3 4.34
8 1 4 7.25
8 2 4 4.32
8 1 5  7.2
8 2 5 4.41
8 1 6 7.19
8 2 6 3.69
8 1 7 6.77
8 2 7 6.09
8 1 8 6.82
8 2 8 5.58
end
Any help is much appreciated.