Gap = (Actual Index Level - Mean Pre-Bubble Ratio) / Actual Index Level

The ratio of the S&P/Case-Shiller Home Price Index Level to the U.S. income index level. The U.S. income index is based upon data reported by the U.S. Department of Commerce. This data is not currently available for individual metropolitan markets. The U.S. Home Price-to-Income Gap is the percentage difference between the current level of the ratio and the mean, pre-bubble ratio. The pre-bubble mean ratio is derived by from data from 1987 through 1999.