Technical Note: Finding the Two Parameters That Specify a Model Schedule of Marital Fertility

The model of marital fertility first proposed by Coale (1971) has proved to be a powerful analytical tool. It has been shown to be a useful component of a full model of age-specific fertility rates (Coale and Trussell 1974) and has been employed in several procedures for estimating fertility (Coale et al. 1975) and mortality (Trussell 1975; Hill and Trussell 1977) from inaccurate and incomplete data. This model has also proved to be a useful descriptive tool in examining whether fertility is natural (Barclay et al. 1976; Trussell 1977) in the sense of Henry (1961) in interpolating five-year rates to obtain single-year rates and in tracing the time sequence of control of fertility (Trussell 1974; Knodel 1977). This latter use has induced us to propose a standard technique for estimating the parameters of the model so that results quoted by different investigators would be comparable. (excerpt)