Modelling Determinants of Time to Age at First Marriage Among Nigeria Women: Stratified-Extended Cox Model

Abstract

The time to age at first marriage is the duration of time between birth until the age at which women began to live with their first partner. This study seeks to apply the Stratified-Extended Cox model (SE-Cox) which addresses the limitations of Cox proportional Hazard model and combines the features of both Stratified Cox and Extended Cox in a single model. The data on age at first marriage of women aged 15-49 from the Nigeria Demographic and Health Survey conducted in 2018 was used. It was observed that Highest educational qualification level, religion, birth cohort and age at first sex violates the Cox proportional hazard assumptions. The Highest educational qualification and religion are assumed to be strata while birth cohort and age at first sex are assumed to be time-varying covariates. The study showed that region, location of residence, wealth index, respondent age at first sex and birth cohort are significant factors that affects the age at first marriage.