CATI response in order to roughly equalize the precision of the estimates for areas with differing levels of predicted mail and CATI response rates. The predicted levels for the 2005 subsampling operation were developed from mail response rate information from the Census 2000 Supplementary Survey and the 2001–2003 ACS test surveys when available and otherwise from a model that included data from the 2000 census; ACS mail and CATI response rate information will be used for all areas in the future.
The MAF plays a critical role as the sampling frame for the ACS. It is the Census Bureau’s inventory of known residential addresses (housing units and group quarters) and selected nonresidential units in the United States and Puerto Rico. It contains mailing and location address information and other attribute information about each address. It also contains geographic codes, such as county and place codes, obtained by linking to the Census Bureau’s Topologically Integrated Geographic Encoding and Referencing (TIGER) database.
For purposes of sampling housing unit addresses for the ACS, the following types of housing unit records are currently included in the ACS version of the MAF (see U.S. Census Bureau, 2006:Ch. 3):
housing units in existence in the 2000 census and those added from the postcensus program to resolve challenges by localities to their population counts (the count question resolution program);
new housing units added from semiannual updates of the U.S. Postal Service’s (USPS) Delivery Sequence File (DSF), along with housing units that were deleted in the 2000 census but continue to appear on the DSF;3
new housing units added from ongoing listings of addresses in areas of new construction that are conducted for the Census Bureau’s other household surveys; and
new housing units added from the Community Address Updating System (CAUS), which annually lists addresses in about 20,000 blocks, out of a total of 750,000 largely rural blocks, where use of the DSF does not provide adequate coverage.
Corrections to housing unit addresses are obtained from all of the above updating programs and from ACS interviewers.
Because the ACS is a continuous monthly survey nationwide, it is es-