U.S. housing markets are the most affordable in the world, at least according to a study of more than 300 metro housing markets in 9 countries conducted by the research group Demographia. Their researchers measured affordability by median home prices and household incomes. U.S. housing markets were found to be more affordable than Canada, the United Kingdom, Ireland, Australia, New Zealand, Singapore, Japan, and China. Some of most unaffordable major markets were Hong Kong; Vancouver; Sydney; Melbourne; and London.