Current and Predicted Fertility using Poisson Regression Model: Evidence from 2008 Nigerian Demographic Health Survey

Adeniyi F. Fagbamigbe, Ayo S. Adebowale

Abstract

Nigeria with persistent high growth rate is among top ten most populous countries. Monitoring key mechanisms of population dynamics particularly fertility in Nigeria is long overdue. Periodical availability of data on fertility and other demographic indices is scarce, hence this study. Our objective was to build a non-linear model to identify fertility determinants and predict fertility using women’s background characteristics.   We used 2008 Nigeria Demography and Health Survey dataset consisting of 33,385 women with 31.4% from urban area. Fertility was measured using children ever born (CEB) and fitted into multi-factors additive Poisson regression models. Respondents mean age was 28.64±9.59years, average CEB of 3.13±3.07 but higher among rural women than urban women (3.42±3.16 vs 2.53±2.79). Women aged 20-24years were about twice as likely to have higher CEB as those aged 15-19years (IRR=2.06, 95% CI: 1.95-2.18). Model with minimum deviance was selected and was used to predict CEB by the woman. (Afr J Reprod Health 2014; 18[1]: 71-83).

 

Keywords: Fertility, Incidence rate ratio, Poisson prediction, children ever born, Nigeria,

 

 

Résumé

Le Nigeria avec un taux de croissance élevé et persistant est parmi les dix pays les plus peuplés. La surveillance des mécanismes clés de la dynamique des populations notamment la fécondité au Nigeria est attendue depuis longtemps. La disponibilité périodique des données sur la fécondité et d'autres indices démographiques sont rares, d'où cette étude. Notre objectif était de construire un modèle non - linéaire pour identifier les déterminants de la fécondité et de prédire la fécondité en utilisant les antécédents caractéristiques des femmes. Nous avons utilisé les données de l’Enquête nigériane démographique et de santé de 2008 qui comprenaient  33 385 femmes avec 31,4 % de la zone urbaine. La fécondité a été mesurée à l'aide des enfants déjà nés

(EDN) et installée dans les additifs multi-facteurs des modèles de la  régression  de Poisson. L’âge moyen des interrogées était de

28,64 ± 9,59 ans, la  moyenne des EDN était de 3,13 ± 3,07, mais plus élevé chez les femmes rurales que les femmes urbaines (3,42 ± 3,16 vs 2,53 ± 2,79). Les femmes âgées de 20 24 années étaient deux fois plus susceptibles d'avoir EDN plus que les femmes âgées de 15-19 ans (IRR = 2,06, IC 95%: 1,95 à 2,18). Un modèle avec la déviance minimum a été sélectionné et a été utilisé pour prédire la l’EDN chez la femme. (Afr J Reprod Health 2014; 18[1]: 71-83).

 

Mots-clés : fertilité,  rapport des taux d'incidence, prédiction de Poisson, enfants nés, Nigeria

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