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Re: st: coefficients on accelerated failure time model level-log (streg)

From   James Henson <>
Subject   Re: st: coefficients on accelerated failure time model level-log (streg)
Date   Thu, 14 Mar 2013 17:40:43 -0400

I ending up find the answer in Wooldridge,2002,p.699. If the variable
is not transformed it is a semielasticity, which makes sense as one
unit change in the variable causes a % change in the survival or
hazard ratio. If a variable is log transformed it is considered an
elasticity. In my case log(t)=log(-xb)+e for log-logistic.

On Tue, Mar 12, 2013 at 6:50 PM, James Henson <> wrote:
> I have the basic understanding of the log-logistic (AFT) model estimates. If the
> coefficient is greater than one the it reduces the survival time, and
> increases survival time for values less than one. I am a little confused on
> if I use a variable such as the log of income (ln(income)) in a level-log
> format. Is it the same as regression (B/100)% change in beta. so, a one
> percent change in income would equal a (B/100) change in survival? Thanks I
> was search for days, but was unable to find the right answer.
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