Sources. SA2 boundaries: Stats NZ (CC BY 4.0, 2025). Facilities: OpenStreetMap (ODbL). NZDep2018: University of Otago.

Method. Haversine estimation with 1.4 winding factor (35 km/h urban, 55 km/h rural). NZDep2018 aggregated SA1→SA2 using modal quintile. ~70% SA2 concordance between 2025 and 2018 boundaries.

Caveats. Car travel only — no public transport. Ecological fallacy applies. Spatially autocorrelated (Moran's I accounts for this).