Transcript Survival Analysis in Stata - Claremont Graduate University

Survival Analysis in Stata
• First, declare your survival-time variables to Stata using stset
• For example, suppose your duration variable is called timevar and it
ranges from 0 to 15 (where 15 marks the end of the sample)
• You observe failure for all durations less than 15 but when timevar =
15 the data is censored
• You need a variable that indicates for which durations you observe
failure; call this variable failureind
• Failureind must take the value 1 when duration is less than 15 and 0
otherwise
• Given timevar and failureind, you tell stata you have duration data
with the command:
Stset timevar, failure(failureind)
The Non-Parametric Hazard Function
• Sts can be used to generate the non-parametric survivor function or the
non-parametric hazard function
• To graph the hazard function, use:
Sts graph, hazard
• To list the hazard function, use:
Sts list, hazard
Survival Models
• Estimate survival models using streg
• Specify which distribution you want using the distribution() option
• You can use the exponential, Weibull, log-normal, log-logistic,
Gompertz, and gamma distributions
Streg x, distribution(exponential)
• You may need to use the nohr option to get Stata to report coefficient
estimates rather than exponentiated coefficients when you are working
with the exponential, Weibull, and Gompertz distributions:
Streg x, distribution(exponential) nohr