Maximum likelihood estimation of survival curve parameters.

A maximum likelihood procedure is presented for the estimation of the parameters in a survival curve which is used in the quantitative investigation of cytological damage resulting from ionizing radiation. This estimation procedure is developed under the assumption that the observations are distributed as independent Poisson random variables. In addition, a weighted least squares procedure, which gives estimates equivalent to the maximum likelihood estimates, is presented. Tests of the model and of the assumed distribution of the observations are given. Two illustrative examples are included.