Remarks on the Use of Probabilities in Demography and Forecasting

Abstract

The concept of “probability” is used as a step in life table construction to get the expected number of survivors in a cohort. However, in traditional texts on demographic methods (e.g., Shryock and Siegel 1976), variance in the number of survivors plays no role. Similarly, concepts of estimation, estimation error, and bias are routinely used, but standard error and sampling distribution are not (except in connection with sample surveys). Although statistically satisfactory accounts of the life table theory have existed for a long time (e.g., Chiang 1968; Hoem 1970), a reason for neglecting population level random variability, and statistical estimation error, has been that the populations being studied are so large that random error must be so small as not to matter, in practice.