Re: st: using roctab when lower values of 'classvar' indicate higher risk

[Ron�n Conroy <rconroy@rcsi.ie>]

On 27 M�rta 2007, at 20:21, Morrison Hodges wrote:

> The manual says that when using 'roctab', higher values of  
> 'classvar' must
> indicate higher risk. I have data using a cardiac variable called  
> ejection
> fraction (EF) as 'classvar', which varies from 0.00 to 1.00, with  
> lower
> values indicating higher risk. The 'refvar' is 'status', with  
> 0=alive and
> 1=dead. The lower the EF the more likely the patient is dead.
Use -logistic- and then -lroc-, which doesn't care which way your  
predictor variable is scaled.

=========
Ron�n Conroy
Royal College of Surgeons in Ireland
rconroy@rcsi.ie
+353 (0) 1 402 2431
+353 (0) 87 799 97 95
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