Rural development labour-outmigration remittances and collective irrigation maintenance in Malawi: a difference-in-differences analysis of village labour-return thresholds

Collective irrigation maintenance in Malawi depends on village labour contributions that labour out-migration and remittance flows may either erode or sustain, yet the threshold at which returning labour becomes sufficient to restore maintenance is unknown. the present analysis characterises the operating characteristics of a before-after-control-impact (BACI) design for estimating that threshold under a declared variance structure. No observational data are used or claimed. The analysis specifies between-cluster standard deviation 6.0, residual standard deviation 4.5 and intraclass correlation 0.640, and evaluates power across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effects of 3, 5 and 8 percentage points. Power curves, minimum detectable effect curves, a scatter fit of power against clusters, residual diagnostics, a kernel density of estimated power and coefficient intervals are reported. The design requires 54 clusters to detect a 5 percentage point effect at 80 per cent power. The village labour-return threshold is estimable only when the design is powered for the intraclass correlation that village-level clustering imposes, and it sets out the identification assumptions and boundary conditions under which the BACI estimator would recover that threshold.