I use SAS's PROC LIFETEST with method=Kaplan-Meier to analyze a data set with censored and uncensored observations. The plot of the cumulative hazard (negative of the log of the survival) versus the survival time shows an increasing-constant-increasing curve. It looks like a 45 degree (slope=1) line from t0 to t1, a horizontal line from t1 to t2, and then a 45 degree (slope=1) line from t2 to infinity. Could you please help me if any model can fit this data? Or, did I do something wrong on the analysis? Thanks.