Interdisciplinary Urban Sociology of Municipal Fire Hydrant Easement Encroachment Permits and Vendor Stall Siting in Lagos's Commercial Streets: A Spatial Regression Discontinuity of Permit Boundaries

The central problem is that permit boundaries are not arbitrary administrative lines: they are spatial thresholds that simultaneously regulate fire-safety access and allocate informal trading space, and their effects on vendor location are confounded with the very street characteristics that determine where hydrants are placed. The paper formalises the permit boundary as a spatial discontinuity in the probability of authorised stall siting and specifies a before-after-control-impact estimator that exploits variation in permit status across hydrant easement boundaries. Because no observational data are used, the analysis characterises the operating characteristics of this design 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 8, 16, 24 and 32 clusters and effects of 3, 5 and 8 percentage points. The design attains 80 per cent power at 54 clusters for a 5 percentage point effect. Permit-boundary discontinuity designs are feasible for Lagos commercial streets only when cluster counts exceed the range typically available to municipal authorities, and it derives the minimum detectable effect curve that makes this constraint explicit.