ABSTRACT
The life-table approach developed in 1958 by Kaplan and Meier (Paper 4) was extended to allow comparison of two or more life-tables via the so-called logrank test. Comparison of survival curves was reduced to estimating the common odds ratio in a series of 2 2 tables. The proportional hazards concept was introduced and a simple estimate of the odds ratio was developed as a weighted average of the odds ratios from the individual tables. Sampling properties of the test and estimator were deduced. Extensions to more than two survival curves were also indicated.
