Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: A Comparison of Two Solution Methods in Estimating Fertility Levels in Nigeria Using Relational Gompertz Model
by A Comparison of Two Solution Methods in Estimating Fertility Levels in Nigeria Using Relational Gompertz Model

Abstract:
One of the most commonly used indirect estimation methods rely on the use of Brass Relational Gompertz Model as modified by Zaba. The model is designed and used as a diagnostic tool and estimation technique for the evaluation and adjustment of fertility estimates obtained from retrospective reports on recent (current) fertility and period fertility (i.e. birth histories). Here, the Gompertz model is fitted to the fertility rates reported by age of mother (15-49) and hence, obtain an estimate of total fertility. In producing estimates of age-specific and total fertility rates, the method seeks to remedy the errors commonly found in fertility data associated with too few or too many births being reported in the reference period, and the under-reporting of a lifetime fertility and errors of age reporting among older women. Quest to improve on and/or at least have other comparative method with the existing technique (i.e. Brass Relational Gompertz Model as modified by Brass) motivate the researcher to develop a simpler and straight forward solution method using Relational Gompertz Model in estimating fertility levels in Nigeria. The newly developed method using the same model assumes that if the mean parities for older women of the fertility age groups are generally unacceptable, and the modified and standardized Relational Gompertz Model is believed to fit the population data; then an estimate of the Total Fertility Rate and hence age specific fertility rates may be obtained. The main focus of the method is to fit the Brass Model by estimating the demographic parameters (where and are the parameters measuring location and dispersion of the distribution while is parameter approximating the total fertility rate) on a certain criterion adopted by the procedures in the method. Once the estimates of these parameters are obtained, the estimation of fitted mean parities and hence the age specific fertility rates are straightforward. The newly developed solution method has been found to favorably compare with the existing method in estimating fertility levels in Nigeria.

Keywords: Gompertz Relational Model, Total Fertility Rates , Mean Parities, Fertility Levels, Current Fertility, Lifetime Fertility

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