"Hierarchical Multiple Regression Analysis of the Effects of Demographic Factors on Population Growth in Nigeria" (1973-2022)

Abstract

Nigeria's population reached an estimated 200 million by 2019 according to the National Population Commission, ranking it seventh globally and posing challenges for resources and infrastructure. This study examines demographic influences on population growth applying World Development Indicators data (1973-2022) using hierarchical multiple regression in three steps. Results showed that Model 1 (net migration only) was significant (R² = .190, p < .01), with migration positively predicting growth. Model 2 added death rate (R² = .196, ΔR² = .006, p > .05), showing no significant improvement; migration stayed significant, but death rate did not. Model 3 included fertility rate, yielding substantial gains (R² = .761, ΔR² = .565, p < .001). Fertility was the strongest positive predictor (p < .001), death rate a significant negative one (p < .001), and migration remained positive. These align with demographic transition theory, emphasizing fertility's dominance in developing nations amid high fertility and declining mortality. Overall, the hierarchical structure of the models demonstrates that although net migration has a consistent positive influence on population growth, the inclusion of fertility rate significantly enhances the model, highlighting its dominant role. The negative effect of death rate in the final model further confirms reductions in mortality contribute to population expansion when fertility levels remain high.