Small Area Population Forecasts: A New Integration of Ratio, Hamilton-Perry and Housing-Unit Methods.

Frédérique Letarte, Ministère des Transports et de la mobilité durable du Québec
Dominic Gagnon , Institut National de Recherche Scientifique (INRS)

Population projections are indispensable for urban planners and policymakers seeking to anticipate the spatial distribution and characteristics of future populations. Yet, at fine geographic scales, traditional cohort-component models face serious limitations due to small population sizes and incomplete migration data. This project develops and validates a hybrid small-area demographic projection model that explicitly integrates demographic mechanisms with housing development forecasts. The model is grounded in the premise that local population change depends not only on fertility, mortality, and migration but also on the spatial supply of housing, itself shaped by real estate dynamics and planning decisions. Combining ratio methods and the Hamilton–Perry approach, the model forecasts population by age and sex, converts it into households, and redistributes them according to available housing units. A novel share-of-housing adjustment ensures that small-area results remain consistent with larger-scale projections. Housing forecasts draw on municipal and developer data for the short term and a logistic growth model for longer-term extensions. Using Canadian census data from 2006 to 2021, the model is applied to 1,040 small-area units in the Quebec City metropolitan region. Preliminary results show that growth concentrates in developing zones, while mature neighborhoods exhibit stagnation or decline linked to aging and smaller household sizes. This approach bridges a critical gap between demography and urban studies, providing a transparent, replicable, and spatially coherent framework for small-area projections—one that can inform housing policy, infrastructure planning, and sustainable territorial development.

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 Presented in Session 52. Flash Session Advances in Subnational and Small-Area Population Analysis