Evaluating Substitution as a Strategy for Handling U.S. Postal Service Drop Points in Self-Administered Address-Based Sampling Frame Surveys

Most addresses on modern address-based sampling frames derived from the U.S. Postal Service’s Computerized Delivery Sequence file have a one-to-one relationship with a household. Some addresses, however, are associated with multiple households. These addresses are referred to as drop points, and the households therein are referred to as drop point units (DPUs). DPUs pose a challenge for self-administered surveys because no apartment number or unit designation is available, making it impossible to send targeted correspondence. The authors evaluate a method for substituting sampled DPUs with similar non-DPUs, which was implemented in the 2021 Healthy Chicago Survey alongside a concurrent survey of the originally sampled DPUs. Comparing aggregate distributions of DPUs and the non-DPU substitutes, the authors observe certain differences with respect to age, employment status, marital status, and housing tenure but no substantive differences in key health outcomes measured by the survey.