Age at union, Sociological Determinants, and Marital Instability in Nigeria: A Survey-Weighted Competing-Risks Analysis

This study examines union instability in Nigeria using the 2018 Nigeria Demographic and Health Survey. We harmonized men’s and women’s files, applied survey weights and stratification, and estimated three complementary models: design-correct logistic regression, survey-weighted Cox proportional hazards, and Fine-Gray competing-risks models that treat widowhood as a competing event. Kaplan–Meier and cumulative incidence functions summarize timing differences; sensitivity analyses add parity as a proxy for marriage-specific investment. Results show higher dissolution risk for women, elevated risk in urban areas, and marked regional variation. Women’s education is positively associated with dissolution, wealth effects are mixed, and age at first union shows weak curvature. Accounting for widowhood avoids overstating dissolution risk.