On Thu, 24 Apr 2003 15:32:24 -0400
"Barlas, Suna" <suna_barlas@merck.com> wrote:
> I also have had the problem that Frank is mentioning below and I do agree
> that there are better ways to model "probability of being on treatment". I
> have played with some non-parametric and semi-parametric models and have not
> concluded that there is a best way. It really depends on the data. Sometimes
> very simple parametric models work pretty well and other times it is better
> to go non-parametric at the first stage and semiparametric at the second
> stage.
>
> Best,
>
> Suna.
>
Just to be clear: the logistic model is a great way to model the propensity for
treatment. The problem I alluded to was in how you adjust for the propensity
score once you've estimated it. -Frank
----
Frank E Harrell Jr Prof. of Biostatistics & Statistics
Div. of Biostatistics & Epidem. Dept. of Health Evaluation Sciences
U. Virginia School of Medicine http://hesweb1.med.virginia.edu/biostat
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