Error in the 2008 to 2015 ACS Year Structure Built Estimates

The U.S. Census Bureau identified a processing error in the year structure built variable for all products since data year 2008. For vacant houses built after 1999, collected year structure built response were processed into an incorrect category instead of the reported write in value. Year structure built for occupied houses was processed correctly. Due to the small number of vacant houses in sample and units that were built after 1999, the impact was minimal. We estimate that 2.25 percent of vacant units or 0.28 percent of all housing units were processed into a different category than reported.

As a result, all 1-, 3- and 5-year estimates from 2008 to 2015 were affected including the 2014 and 2015 Supplemental Estimates.  Specifically, the following detailed tables and derived products available on American FactFinder were affected:

• B25034 (Year Structure Built)
• B25035 (Median Year Structure Built)
• K202505 (Year Structure Built table in the Supplemental Estimates)
• R2502 (Ranking Table: Percent Housing Units that Were Built in 2014 or Later)
• GCT2502 (Geographic Comparison Table: Percent of Housing Units that Were Built in 2014 or Later)
• S0201 and S0201PR (Selected Population Profiles in the United States and Selected Population Profiles in Puerto Rico)
• DP04 (Selected Housing Characteristics Data Profile)
• CP04 (Comparative Housing Characteristics Profiles)

The 1- and 5-year Public Use Microdata Sample (PUMS) files for the YBL variable (Year Structure Built) were also affected between 2008 and 2015. As with the tabulated data, the individual records for YBL do not correctly include the write in value for vacant houses built after 1999. The error will be corrected beginning with data collection year 2016.