Model Fertility Schedules Revisited: The Log-Multiplicative Model Approach

This paper reconsiders Coale and Trussell's (Population Index, 1974) specification of model fertility schedules by age. It formally presents model fertility schedules within the framework of categorical data analysis. Specifically, births are assumed to follow an independent Poisson distribution for each age interval of each population. Identification and estimation problems are discussed. It shows that the Coale-Trussell's specification corresponds to Goodman's (The Analysis of Cross-Classified Data Having Ordered Categories, 1984) log- multiplicative model. Following Goodman's algorithm, the paper simultaneously estimates Coale and Trussell's v(age), m, and M through an iterative maximum-likelihood procedure. This is demonstrated with the same data that were used in Coale-Trussell's article. It is shown that the new estimates are superior.