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Re: st: Bland Altman Plots for Clustered Data


From   David Airey <[email protected]>
To   "[email protected]" <[email protected]>
Subject   Re: st: Bland Altman Plots for Clustered Data
Date   Fri, 17 Apr 2009 14:00:51 -0500

There is a Berkley Press statistics paper on BA problems with replicated data you should google for... Don't have the reference handy, sorry.

Sent from my iPhone

On Apr 17, 2009, at 1:56 PM, "Ploutz-Snyder, Robert (JSC-SK)[USRA]" <[email protected] > wrote:

Statalisters;
In response to a reviewer's suggestion, I'm creating some Bland Altman plots (using concord.ado) on a panel dataset, where two parallel observations are made on subjects repeatedly over different speeds at a task. I'm doing this for a few outcomes, but have shown a sample below from the first 2 subjects:
    +---------------------------------------+
    | subject   speed       rer0       rer1 |
    |---------------------------------------|
 1. |       1       0   .9453608   .8185958 |
 2. |       1       2   .7703036   .7761767 |
 3. |       1       3   .7817145   .8262445 |
 4. |       1       4   .8781749   .8886828 |
 5. |       1       5   .9401777   1.012666 |
 6. |       1       6   .9988574   1.080287 |
    |---------------------------------------|
 7. |       2       0   .9489434   .8451807 |
 8. |       2       2   .8366485   .7932663 |
 9. |       2       3   .8556526   .8569991 |
10. |       2       4   .8677133   .8986406 |
11. |       2       5    .946165   .9572051 |
12. |       2       6   .9317179   .9195401 |
    |---------------------------------------|

I don't normally use BA plots, but for now I'm trying to appease a pesky reviewer. My question is targeted to those of you who use or have an interested in the BA plots... Since my data are clustered on subject, what's the best approach to plot BA-like associations between means and diffs on the two outcomes? I'm trying to limit the number of BA plots, as the paper already has better plots showing the effects of speed (and other vars) on these two repeated observations. But I have a reviewer who's really stuck on the BA plot.

I'm starting with:

concord rer0 rer1, loa(regline noref)

But troubled by the clustering of observations within subject.


Ideas?
Rob

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