The abridged census method as an estimator of lifetime risk

The abridged census estimator, also known as Weinberg's shorter method, is a device used to estimate lifetime incidence from the observed age distribution of a population at risk coupled with data on the current prevalence of a mental disorder. This method, which still enjoys considerable popularity, should have been replaced many years ago by more accurate techniques for making such estimates using similar information. In particular, the abridged census method uses the assumption that the remaining life expectancy of incident cases equals that of non-cases. This assumption is likely to lead to an underestimate of the lifetime risk. Two examples are presented from published literature which illustrate some problems encountered with the use of the abridged census method. Some alternative estimation methods are presented which can be implemented using only a hand calculator and which lead to more accurate results.