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st: stcurv,cumhaz


From   "Paul E. Karner" <pkarner@iie.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: stcurv,cumhaz
Date   Tue, 11 Nov 2003 20:56:41 -0500

Hello,

I have two related questions regarding STATA's cumulative hazard calculations when it produces the chart generated by the command stcurv,cumhaz following a Weibull or Gamma parametric regression.

1)  Do the two numbers correspond to the minimum and maximum cumulative hazards?  In some instances I am getting a nonzero, and in others a zero number for the lower value on the chart.

2)  If these are the min and max, why are they not the same as when I use the predict,hazard command and manually sum up the hazards when the covariates are set to their mean values?  Perhaps STATA evaluates a continuous function (integral) in calculating its cumulative hazards, resulting in the discrete sum over the time interval being different?

I'd appreciate any help you may be able to provide.

Thank you,

Paul Karner



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