An alternative approach to statistical age-period-cohort analysis.

Age-period-cohort analysis has generated considerable interest in epidemiology, but the model has fundamental problems which have been discussed by Kupper et al. While one can agree that the age-period-cohort model should be used with caution, it should also be noted that some useful inferences can be made with the model. The problems raised by Kupper et al. are discussed in terms of estimable functions of the parameters, which are not affected by arbitrary constraints on the parameters. The use of these methods are illustrated and specific examples presented where age-period-cohort models can be used effectively.