Militia co-optation and electoral violence in Nigeria's off-cycle gubernatorial contests: a difference-in-differences estimation of political exclusion effects on communal security

The study treats the off-cycle contests as a natural laboratory in which staggered election timing generates variation in exposure to militia co-optation, and it characterises the operating characteristics of a before-after-control-impact estimator under a declared variance structure with an intraclass correlation of 0.64, a between-cluster standard deviation of 6.0 and a residual standard deviation of 4.5. Power was estimated across 2000 design cells spanning cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The design requires 54 clusters to detect a 5 percentage point effect at 80 per cent power. Political exclusion operates through militia co-optation as a mechanism that degrades communal security, and it specifies the identification assumptions, the estimand and the boundary conditions under which the design yields credible inference. The contribution is a design-based framework for studying electoral violence and communal security in Nigeria, together with a transparent account of the statistical power that such a framework requires.