Compare methods

	Housing Affordability Index	Smart City Index
Field	Urban Studies	Urban Studies
Family	Process / pipeline	Process / pipeline
Year of origin	2006	2011
Originator	Housing-economics tradition (ratio measures); Michael E. Stone (residual-income approach)	Giffinger et al. (smart-city dimensions); Caragliu, Del Bo & Nijkamp (smart-city concept)
Type	Index/ratio comparing housing cost to household income	Composite index aggregating indicators across smart-city dimensions
Seminal source	Stone, M. E. (2006). What is housing affordability? The case for the residual income approach. Housing Policy Debate, 17(1), 151–184.	Caragliu, A., Del Bo, C., & Nijkamp, P. (2011). Smart cities in Europe. Journal of Urban Technology, 18(2), 65–82.
Aliases	Median Multiple, Housing Cost Burden Ratio, Residual Income Affordability, NAR Housing Affordability Index	Smart City Ranking, Cities in Motion Index, Smart-City Composite Indicator, Smart City Performance Index
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.	A smart city index is a composite indicator that scores and ranks cities on how 'smart' they are across several dimensions — typically economy, people, governance, mobility, environment and living. Each dimension gathers many raw indicators that are normalised onto a common scale, weighted, and aggregated first into dimension scores and then into a single overall number. Prominent examples such as the European smart-cities ranking of Giffinger and colleagues and the IESE Cities in Motion Index made this six-axis framing standard, turning a sprawling, contested concept into a benchmark cities can be compared on.