An address-based geospatial linkage workflow for assigning New Zealand Index of Deprivation measures across census...

Assigning area-level socioeconomic measures to street addresses across historical and contemporary census years requires harmonising address, geography and deprivation datasets that change over time. This methods article describes a reproducible workflow and online implementation for assigning New Zealand Index of Socioeconomic Deprivation (NZDep) measures to street addresses for census years 1991-2023. The method integrates public Land Information New Zealand address data, openly licensed postcode boundary polygons, Stats NZ census geographies and University of Otago NZDep datasets into an indexed SQLite lookup database and Shiny address-lookup tool (https://bit.ly/nzdep). Address labels are standardised, address points are spatially linked to year-specific census geographies, and geography identifiers are joined to corresponding NZDep values. Raw NZDep scores are converted to census-year-specific national percentile ranks, allowing relative deprivation position to be expressed on a consistent 1-100 scale across census periods. The workflow supports unit-level address lookup where available and base street-address lookup only where deprivation assignment is unambiguous. The final database contained 2405,589 address records and achieved 99.65% completeness across 16,839,123 potential address-year NZDep assignments.