Compare methods

	Housing Affordability Index	Gentrification Analysis
Field	Urban Studies	Urban Studies
Family	Process / pipeline	Process / pipeline
Year of origin	2006	1979
Originator	Housing-economics tradition (ratio measures); Michael E. Stone (residual-income approach)	Ruth Glass (term, 1964); Neil Smith (rent-gap theory)
Type	Index/ratio comparing housing cost to household income	Pipeline for detecting and measuring neighbourhood socioeconomic upgrading and displacement
Seminal source	Stone, M. E. (2006). What is housing affordability? The case for the residual income approach. Housing Policy Debate, 17(1), 151–184.	Smith, N. (1979). Toward a theory of gentrification: A back to the city movement by capital, not people. Journal of the American Planning Association, 45(4), 538–548.
Aliases	Median Multiple, Housing Cost Burden Ratio, Residual Income Affordability, NAR Housing Affordability Index	Gentrification Measurement, Neighbourhood Upgrading Analysis, Rent Gap Analysis, Displacement Risk Analysis
Related	4	4
Summary	A housing affordability index summarises how the cost of housing in a city or market relates to what households can pay, condensing prices, rents and incomes into a single interpretable number. The simplest forms are ratios — the median house price divided by median income, or housing outlays as a share of income — while the residual-income approach championed by Michael Stone instead asks what is left for everything else after housing is paid. Together these measures let analysts compare affordability across places and over time, flag cost-burdened populations, and track housing stress as markets shift.	Gentrification analysis is the set of methods used to detect, measure, and map the process by which a previously disinvested, lower-income neighbourhood is upgraded through an influx of capital and higher-status residents, often displacing the existing population. It typically combines repeated small-area census data on income, education, tenure, and rents with housing-market indicators to compute change indices that flag where socioeconomic status is rising fastest. Grounded in Neil Smith's 1979 rent-gap theory, the analysis frames gentrification as the reinvestment of capital in places where the gap between actual and potential land rent has grown large enough to be profitable.