Demographic Research (Mar 2002)
Tempo-Adjusted Period Parity Progression Measures, Fertility Postponement and Completed Cohort Fertility
Abstract
In this paper we introduce a new set of tempo-adjusted period parity progression measures in order to account for two distinct implications caused by delays in childbearing: tempo distortions imply an underestimation of the quantum of fertility in observed period data, and the fertility aging effect reduces higher parity births because the respective exposure is shifted to older ages when the probability of having another child is quite low. Our measures remove the former distortion and provide means to assess the latter aging effect. The measures therefore provide a unified toolkit of fertility indices that (a) facilitate the description and analysis of past period fertility trends in terms of synthetic cohort measures, and (b) allow the projection of the timing, level and distribution of cohort fertility conditional on a specific postponement scenario. Due to their explicit relation to cohort behavior, these measures extend and improve the existing adjustment of the total fertility rate. We apply these methods to Sweden from 1970 to 1999.
