Source: U.S. Department of Housing and Urban Development
Latest Data: 2019
Frequency: Annual
Contact: Rachelle Levitt, Rachelle.L.Levitt@HUD.gov

The number of total building permits and building permits for single-family homes comes from the  Building Permits Survey conducted by the U.S. Census Bureau, which describes the survey as follows:  “The purpose of the Building Permits Survey is to provide national, state, and local statistics on new privately-owned residential construction. The United States Code, Title 13, authorizes this survey, provides for voluntary responses, and provides an exception to confidentiality for public records. Over 98 percent of all privately-owned residential buildings constructed are in permit-issuing places. Data collected include number of buildings, number of housing units, and permit valuation by size of structure. Data on permits issued for new construction are available monthly and annually since 1959; reported data are for permit issuing activity taking place during the applicable reference period. Prior to 1959, data were collected by the Bureau of Labor Statistics. A monthly survey [consists] of 9,000 selected permit-issuing places; and an annual census of an additional 11,000 permit places that are not in the monthly sample. Places that exceed a cutoff value, which varies by state, were selected with certainty. Remaining places were sampled at a rate of 1 in 10. Monthly estimates represent all permit-issuing places nationwide. If a survey report is not received, missing data on permits for new construction are imputed except for places that are also selected for the Survey of Construction (SOC)."

Economists use index numbers for quick comparisons between sets of data across time. The Building Permits, Single Family (Indexed to 2005) measure is calculated by identifying 2005 as the "base year" and scaling all of the other ‘Building Permits , Single Family’ results off of that year.

For example, the ‘Building Permits - Single Family’ value for Alabama in 2005 is represented by 1.0 (obtained by dividing the value by itself, 24132/24132 = 1.0) and the numbers from other years are similarly scaled down. The ‘Building Permits - Single Family: 2005 = 1.0’ value for 2018 is 0.53 obtained by dividing 2018 ‘Building Permits - Single Family’ value by the base year’s ‘Building Permits - Single Family’ value ( 24678/24132 = 0.4729)

-- http://www.census.gov/construction/bps/about_the_surveys/