Border closure regimes and informal cross-border trade security in the ECOWAS corridor: a computed-control evaluation of market-displacement effects on smuggling networks

Because no observational data on border closures are used or claimed, the analysis characterises the design's power to detect market-displacement effects under a declared variance structure with a between-cluster standard deviation of 6.0, a residual standard deviation of 4.5, and an intraclass correlation of 0.640. Power was estimated across 2000 design cells defined by cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points, with 2000 replications per cell. The results indicate that 54 clusters are required to detect a 5-percentage-point displacement effect at 80 per cent power. The BACI estimator's operating characteristics impose a binding constraint on the study of border closure regimes: the cluster counts typical of ECOWAS corridor research are insufficient to detect the displacement effects that the policy literature hypothesises. The contribution is a design-based account of what can and cannot be learned about smuggling-network displacement from the observational designs currently used in the field.