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Re: st: Simplification of formula in logistic regression


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Simplification of formula in logistic regression
Date   Sun, 15 May 2011 15:49:37 +0100

I don't know what "statistically correct" would mean here. If you
think your model is useful, there are no grounds for coarsening it. If
the implication is that clinicians can't understand or don't need to
understand the internals of the formula you can think of encapsulating
the details in a Stata do-file or some equivalent in other software.

A broad issue is that detailed models optimised to fit particular
datasets often perform poorly on other data.

Nick

On Sun, May 15, 2011 at 3:43 PM, Mikkel Brabrand <mikkel@brabrand.net> wrote:

> I have performed a logistic regression analysis including five variables and one outcome. However, I would like to simplify the formula significantly for clinical use. So, instead of the formula been something like -12.22+2.33*systolic blood pressure-1.21*temperature etc., I would like to make a scoring system where the score is calculated on basis of the measured values of the vital signs.
>
> An example could be something like this
>
> .................2 points..1 point...0 points...1 point.....2 points
>
> Pulse   ...........-30........31-50....51-100....101-200..201-
>
> Sys. BP.........-60........61-100..101-200...201-
>
> However, I have no idea how to find the optimal cut-off points. Do any of you have a suggestion how to do this statistically correct?

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