This program can be used heuristically for developing classifiers for predicting risk groups with survival data. Conceptually the patients with survival time greater than a landmark time T can be considered the low risk class and those with survival less than T as the high risk class. T should be selected to approximately maximize the difference in survival distributions between the two classes and the prevalence determined accordingly. For example, if 60% of patients fail mostly within 3 years, and the remaining are cured, it would be reasonable to use T=3 years and a prevalence of 60% for purposes of sample size planning. This heuristic approach should work as long as the proportion of patients who will be censored (lost to follow-up) before time T is small.