Improving the Efficiency of Address-Based Frames with the USPS No-Stat File

at RTI International

Address-Based Sampling (ABS) frames are typically based on the Computerized Delivery Sequence (CDS) file, which the United States Postal Service (USPS) makes available through licensing agreements with qualified vendors. Research based on the CDS file has found the coverage of ABS frames for in-person surveys to be sufficient in urban areas but problematic in rural areas. Because of low rural coverage, researchers often resort to hybrid sampling frames based on both ABS and traditional field enumeration (FE). With a hybrid frame, areas where ABS coverage is expected to be sufficient are allocated to ABS while areas where poor ABS coverage is anticipated are allocated to FE. The more areas that are allocated to the ABS portion of the hybrid frame, the greater the cost savings. Since 2009, the USPS has made available the No-Stat file, a supplement to the CDS file that contains approximately seven million predominately rural locatable addresses not found on the CDS file. Previous research has indicated that supplementing the CDS file with the No-Stat file could be a cost-effective strategy for improving rural ABS coverage for in-person surveys. Although the overall coverage gains provided by the No-Stat file are modest, No-Stat addresses are clustered in relatively small geographic areas. This clustered aspect of No-Stat addresses means that they could significantly improve ABS coverage in some localized areas. In a hybrid frame design, these coverage improvements move some areas that otherwise would rely on FE to the ABS portion of the frame, which lowers field costs. This paper measures the efficiencies that are gained by including the No-Stat file for a specified hybrid frame design and coverage estimator. Efficiency gains vary widely across states, and are most significant for higher coverage thresholds.