PROPENSITY SCORE METHODOLOGY FOR EXAMINING THE EFFECT OF EDUCATION ON ATTITUDE TOWARDS DOMESTIC VIOLENCE IN NIGERIA

Abstract

Background: Experimental studies remain the gold standard in making causal inference. However, using experimental studies to estimate the effect of education on attitude towards domestic violence (ATDV) was not feasible due to ethical issues. This challenge can be overcome using Propensity Score Methodology (PSM). The PSM is a statistical technique used in observational studies to estimate the effect of interventions by accounting for covariates that predicts the treatment. Therefore, PSM was used to investigate the effect of education on ATDV among men and women in Nigeria.

Methods: A total of 14,495 and 33,419 records were extracted for men and women respectively from the 2016-2017 Multiple Indicator Cluster Survey (MICS) in Nigeria. The outcome variable was ATDV. ATDV was measured by asking the respondents the question, “In your opinion, is a husband justified for hitting or beating his wife if she, goes out without telling him, neglects the children, argues with him, refuses to have sex with him, or burns the food.” Any respondent who says yes to any of the five options has justified domestic violence and whosoever that says no to all does not justify domestic violence. The treatment variable was education while the covariates were age, residence, geopolitical zones, marital status, ethnicity, parity, wealth index, alcohol use and media exposure (use of television or radio). The descriptive statistics were presented and multinomial logit regression was used to assess selection bias among the levels of education. Propensity scores (PS) and PS weights were generated for the treatment variable and average treatment effects on ATDV were estimated using logistic regression that combined regression adjustment and inverse-probability weighting. Odds ratios and 95% confidence interval were presented. Results: The mean age of men and women were 30.8±10.2 years and 29±9.4 years respectively. About 16% men had tertiary education while lower proportion (14%) of women had tertiary education. The proportion of men and women who justified DV was 22% and 34.5% respectively. There were more of uneducated men among Hausas (26.3%) compared to Igbo (p<0.001). Similarly, tertiary education was more pronounced among the Yoruba women (23.2%) compared to the lower proportion (3.9%) among Hausa women (p<0.001). Result from the multinomial logit model showed the existence of selection bias between the covariates and level of education (p<0.05). After the estimation of PS, the selection bias was effectively corrected (SD diff ≈ 0, Variance ratio ≈ 1). Results from the PSM showed that the odds of ATDV decreased as level of education increased. Men (AOR = 0.84, 95% CI: 0.78, 0.92) and women (AOR=0.94, 95%CI: 0.80, 2.22) who attained tertiary education were less likely to justify DV in comparison to their uneducated counterparts. Conclusion: Education played a crucial role in ATDV among men and women in Nigeria. Tertiary education was protective for ATDV among men and women. The use of PSM effectively controlled for selection bias in estimating the effect of education on ATDV. PSM will enable researchers make causal inference from non-experimental/ cross-sectional studies in situations where randomized control trials are not feasible.