Rural Interdisciplinary Sociology of Pastoralist Grazing Corridor Mapping Disputes and Inter-Community Boundary Contestation in Kenyan Rangelands: A Spatial Regression Discontinuity Analysis of Corridor Demarcation Thresholds

Pastoralist grazing corridors in Kenyan rangelands are demarcated by administrative thresholds — a fixed distance from a water point, a fixed width, a fixed number of member households — and disputes between communities frequently crystallise around whether a corridor boundary was drawn on the correct side of such a threshold. Spatial regression discontinuity (RD) is the natural design for estimating the causal effect of falling just inside versus just outside a demarcated corridor, yet its operating characteristics in the small-cluster, spatially autocorrelated settings typical of rangeland administrative units have not been characterised. Power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The analysis indicates that 52 clusters are required to detect a 5 percentage point effect at 80% power under this variance structure, and that the minimum detectable effect at 80% power falls steeply as cluster count rises from 8 to 32. The contribution is a design rule for corridor demarcation studies: RD estimates of boundary effects are only credible when the cluster count is sufficient to separate the discontinuity from the intraclass correlation that rangeland administrative units impose.