Finally, there is credible housing affordability data from China. For years, analysts have produced “back of the envelope” anecdotal calculations that have been often as inconsistent as they have been wrong. The Economist has compiled an index of housing affordability in 40 cities, which uses an “average multiple” (average house price divided by average household income) (China Index of Housing Affordability). This is in contrast to the “median multiple,” which is the median house price divided by the median household income (used in the Demographia International Housing Affordability Survey and other affordability indexes). The Demographia Survey rates affordability in 9 geographies, including Hong Kong (a special administrative region of China). The average multiple for a metropolitan market is generally similar to the median multiple.