New Approach for Handling Drop Point Addresses in Mail/ Web Surveys

Abstract

The purpose of this paper is to introduce the concept of drop unit substitution in address-based samples for mail and web surveys. A drop point is a single US Postal Service (USPS) delivery point or receptacle that services multiple businesses, families, or households (USPS, 2017). Residential drop units are the individual housing units served by the drop point address. For the most part, address-based sampling frames list the number of units at a drop point address but will not contain information identifying specific units. Drop units comprise less than 2 percent of all residential addresses in the United States (McMichael, 2017), but they tend to be concentrated in certain large cities. In Queens, New York, for example, drop units constitute 27 percent of residential housing units. The problem with drop units for address-based surveys with mail contacts is that, without names or unit identifiers, there is no way to control which unit receives the various mailings. This limitation leads to distorted selection probabilities, renders the use of cash incentives by mail impractical, and precludes traditional methods for mail nonresponse follow-up, thus resulting in higher nonresponse. Alternatively, excluding drop units results in coverage error, which can be considerable for some subnational estimates. The authors propose a substitution approach when a drop unit is sampled—in other words, replacing the unit with a similar nearby unit in a non–drop point building.

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

“…A nuisance address type practitioners are bound to encounter when using an ABS frame, albeit at different rates across the country, is a DP address, a grouping of two or more addresses linked to a single mail receptacle for which no secondary address information (e.g., apartment number, unit designation) is available. Using data from the 2021 HCS, this article presented an empirical evaluation of a substitution method (Harter et al 2022) that replaces any sampled DPU with a nearby non-DPU.…”

“…In Figure 3A, the two buildings look quite similar, yet that is not necessarily the case for the pair shown in Figure 3B. See Harter et al (2022) for more discussion of qualitative comparisons of DPUs and non-DPUs in the 2020 RECS, a nationally representative survey that implemented a comparable substitution approach.…”

“…In this article we present an evaluation of a substitution approach for handling DPUs (Harter, McMichael, and Deng 2022) that was implemented in the 2021 Healthy Chicago Survey (HCS), a self-administered, mail-contact survey in which DPUs account for approximately 14 percent of all addresses in the ABS frame. The first step involved expanding the frame to include one line per DPU such that each was eligible to be sampled.…”

Mail to One or Mail to All? An Experiment (Sub)Sampling Drop Point Units in a Self-Administered Address-Based Sampling Frame Survey

“…Numerous strategies have been proposed to handle drop points in selfadministered mail contact surveys. These range from accepting the risk of coverage bias and eliminating them from the ABS frame altogether, or at least eliminating those larger than some prespecified threshold (RTI International 2021), merging on partially complete unit information (Kalton, Kali, and Sigman 2014) from supplemental data sources such as the No-Stat file (Shook-Sa et al 2013), or substituting the sampled drop point with the nearest nondrop point address (Harter, McMichael, and Deng 2022;Lewis, McMichael, and Looby 2023). Amaya (2017) identifies two other options: sampling all units within the selected drop point or selecting a subsample of units within the selected drop point.…”