Analysis of survival data by the proportional odds model.

A model is presented for the analysis of lifetime data in which the rates of mortality for separate groups of patients converge with time. A non-parametric estimate is given for the survivor function. The theoretical basis for the model assumes that prognostic factors have a multiplicative effect on the odds against survival beyond any given time. The model is fitted to data using maximum likelihood estimation, and an example of its use in the analysis of a lung cancer trial is given.