st: semiparametric mixture cure models

["Sridhar Telidevara" <sridhar.telidevara@gmail.com>]

Are there any stata routines for estimating a semiparametric mixture cure
model with fixed covariates?  The data have 30,000  observations and the
duration of observation is in days ( 1 day to 1096 days). 

 

I have estimated several parametric mixture cure models and they did not
yield good results. Cure percentage was very low, the fit had long tails and
the median survival time is greater than 1096 days. Therefore, there exists
an identification problem.

 

Further, 

 

1.       since the data is in days, is stset enough or episode splitting is
required?

 

2.       Convergence problems with the EM algorithm and the bootstrapping
procedures if the data is in days.

 

3.       If I have to group the data to estimate a semiparametric mixture
cure model what is the optimal way to group the data? 5 days, 10 days? 30
days?

 

Thank you for your help,

 

Sridhar Telidevara

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