Browsing by Author "Gayawan, E."

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Bayesian geo-additive spatial modelling of HIV prevalence using data from population-based surveys
(Polish AIDS Research Society, 2019) Adebayo, S. B.; Gayawan, E.; Fagbamigbe, A. F.; Bello, F. W.
Introduction: Estimates of human immunodeficiency virus (HIV) prevalence in Nigeria have been based on the data from HIV surveillance and sentinel studies among pregnant women attending antenatal clinics at some selected sentinel sites. However, such data overestimate HIV prevalence. This paper explores possible geographical variations in HIV prevalence among the general population of males and females based on two waves of the National HIV/acquired immune deficiency syndrome (AIDS) and Reproductive Health Surveys. Material and methods: Data were extracted from the cross-sectional 2007 and 2012 National HIV/ AIDS and Reproductive Health Serological Surveys of men (15-64 years) and women (15-49 years) covering all states of Nigeria. Bayesian geo-additive modelling technique was employed for analysis. Appropriate prior distributions were assigned to the different types of variables in the models and inference was based on the Markov Chain Monte Carlo (MCMC) technique. Models of different specifications were considered. Results: The findings reveal significant spatial variations at a highly disaggregated level of states in Nigeria. The nonlinear effects of respondents’ age show a similar pattern of HIV prevalence for male, female and the combined respondents, implying that HIV prevalence is peak among middle-age individuals, from where it declines with age. Also, the results reveal a downward change in HIV prevalence in Nigeria between 2007 and 2012. Conclusions: When these findings are taken into consideration in designing intervention strategies, it is believed that each state can be targeted with the right intervention(s). This can also lead to efficient utilization of the scarce resources witnessed globally and more importantly with the economic recession in Nigeria.
Modelling determinants of geographical patterns in the marital statuses of women in Nigeria
(Springer, 2021) Ononokpono, D. N.; Adebola, O. G.; Gayawan, E.; Fagbamigbe, A. F.
Marriage is an important social, cultural, and biological aspect of human life but is often affected by societal changes leading to differences in family formation and reproductive behaviour. Changes in marital patterns are component of transformations in a society’s social structure. Variations in marriage patterns exist within and across countries and over time. We examine the trends and spatial patterns of marital statuses among women of reproductive age (15–49 years) in Nigeria and further determine the associated factors based on the country’s north–south divide. Data were sourced from the Nigeria demographic and health survey conducted in 2003, 2008, 2013, and 2018, and the marital patterns were classified into four categories: never married, married, cohabiting, and formerly married. A Bayesian multinomial spatial model that simultaneously estimates parameters of different forms through a geo-additive predictor was adopted, and inference was based on Markov chain Monte Carlo. Findings reveal a north–south divide in marriage patterns. Women in the northern part of the country have a higher likelihood of being in marital union, while those in the south have a higher likelihood of cohabitation. A somewhat east– west divide was obtained for formerly married. Religion and ethnicity were found to be the major factors that account for differences in marital patterns across the divide and based on rural and urban residency. Cultural practices dictated by these variables would, therefore, continue to shape marital patterns and, by extension, fertility in Nigeria. The factors are hence important to be considered in marriage related policy formulation.