The NAHB/Wells Fargo Housing Market Index (HMI) is based on a monthly survey of NAHB members designed to take the pulse of the single-family housing market. The survey asks respondents to rate market conditions for the sale of new homes at the present time and in the next six months as well as the traffic of prospective buyers. An index is calculated for each series by applying the formula “(good – poor + 100)/2” or, for Traffic, “(high/very high – low/