May include people in institutions. Indicators of housing affordability usually focus on the ratio between housing costs and household income (AHURI, 2005). One useful and common measure of housing affordability is the housing cost overburden, which measures the proportion of households who spend more than a given share of household income on housing costs. Figure 3 illustrates the proportion of households who spend more than 40% of their income on housing costs, based on household survey data.