An African Fertility Standard for the Relational Gompertz Model

Tom A. Moultrie, University of Cape Town
Reinier van Gijsen, University of Cape Town

The Relational Gompertz model of fertility, first proposed by Brass 30 years ago, has entered the canon of demographic techniques. However, the standard proposed by Booth for use with the model causes fertility at the oldest ages to be systematically under-estimated - typically by a factor of 3 or more. This paper presents a new standard appropriate to analyzing the shape and level of African fertility using data from more than 60 DHS surveys across the region. The approach of using Coale-Trussell fertility schedules adopted by Booth to derive her standard is found to be ineffective in solving the problem identified. Parametric models of fertility proposed by Brass and Hadwiger are considered instead. The African standard and its associated coefficients are derived from the Brass model. The revised standard holds the promise for better estimation of fertility from limited and defective data in Africa.