Hello,

I'm trying to compare different techniques for measuring the electrical activity in hearts using idfferent types of catheters. There are multiple measurements involved such that I have 5 rabbit hearts, each heart was measured in 9 spots, each spot has 10 measurements, and it was measured using 3 different catheters. The goal of the analysis is to compared the 3 different catheters, comparing the new OT catheter with the older V cathether and H catheter. An example of the data is below (although for simplicity limited to 3 rabbits, measured in 2 spots, with 3 repeated measurements), using dataex.

Ordinarily, I would simply use
to compare the limits of agreement between two of the measurements, the new OT cathether and the old V catheter. However, that doesn't account for the nested design or repeated measurements. Same with doing a paired t-test,
, would tell me if the mean difference between these two measures was different from zero, but again not account for the nested deign and multiple measurements.

Is there some method for accounting for repeated measures in these analyses when using a Bland Altman analysis? I'm using Stata version 12 on Mac.

Help is much appreciated.

Thanks,

Chris

I'm trying to compare different techniques for measuring the electrical activity in hearts using idfferent types of catheters. There are multiple measurements involved such that I have 5 rabbit hearts, each heart was measured in 9 spots, each spot has 10 measurements, and it was measured using 3 different catheters. The goal of the analysis is to compared the 3 different catheters, comparing the new OT catheter with the older V cathether and H catheter. An example of the data is below (although for simplicity limited to 3 rabbits, measured in 2 spots, with 3 repeated measurements), using dataex.

Code:

* Example generated by -dataex-. To install: ssc install dataex clear input byte(rabbit spot measure) float(ot v h) 1 1 1 4.7 2.8 5.1 1 1 2 5.2 2.4 5.3 1 1 3 3.6 2.9 4.8 1 2 1 1.3 1.3 3.7 1 2 2 1.3 1.3 3.7 1 2 3 1.3 1.3 3.7 2 1 1 5 3.1 1.8 2 1 2 5 3.1 1.8 2 1 3 5 3.1 1.9 2 2 1 4.9 3.1 1.8 2 2 2 5 3.1 1.9 2 2 3 4.9 3.1 1.9 3 1 1 5.2 7.1 7.1 3 1 2 5.2 7 7 3 1 3 5.3 7 7.1 3 2 1 5.2 7 7 3 2 2 5.2 7 7.1 3 2 3 5.2 7 7 end

Code:

batplot ot v

Code:

ttest ot == v

Is there some method for accounting for repeated measures in these analyses when using a Bland Altman analysis? I'm using Stata version 12 on Mac.

Help is much appreciated.

Thanks,

Chris

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