[R] understanding the output from survival analysis

Terry Therneau therneau at mayo.edu
Tue Mar 10 15:01:41 CET 2009


> Why do I get different sign of the coefficients of covariates when I run the
> semi-parametric proportional hazard model (coxph) compared to the parametric
> proportional hazard model (survreg)?

  Survreg models the time till death, a postive coefficient --> a longer time.
  Coxph models the death rate, a positive coefficient --> higher death rate.
  
  So in the first a positive is good, in the second it is bad.
  
> Anyone with experience in extracting information form survreg to make
> predictions are free to contact me.

  Commonly one would use predict(fit) to get predictions.  There are several 
options.
  
  	Terry Therneau




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