Introduction to Aalen (1978) Nonparametric Inference for a Family of Counting Processes

Odd Olaf Aalen was born in 1947 in Oslo, Norway, and he grew up there. He completed a Masters degree thesis at the University of Oslo in 1972 under the guidance of Jan Hoem. This thesis developed some methods for estimating the efficacy and risks involved in the use of intrauterine contraceptive devices (IUDs). Hoem had suggested that time-continuous Markov chains might be useful for modeling the progression of events experienced by a woman following the insertion of an IUD, as this was a model that Hoem had found useful in other contexts. The need to fit such models non-parametrically started Aalen thinking about the approach that he was to develop fully in his ground-breaking 1978 paper that is reprinted here.