The stan code I used is a translated version from OPENBUGS code from Leuk: Cox regression: http://www.openbugs.net/Examples/Leuk.html

My problem here is that with a good sample size (62 events samples, 2 independent variables), I got very different cumhaz from cox model. The coefficients are quite close (20% difference), but the cumhaz has 10 times of difference. I wonder what I did wrong or how can I improve my model / prior, etc to solve this situation?

Thank you very much for your advice.