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

Abstract

Practitioners utilizing an address-based sampling frame for a self-administered, mail contact survey must decide on how to handle drop points, which are single delivery points or receptacles that service multiple households. A variety of strategies have been adopted, including sampling all units at the drop point or subsampling just one (or a portion) of them. This paper reports results from an experiment fielded during the 2021 Healthy Chicago Survey aimed at providing insight into whether there are any substantive differences between these approaches. We find that a subsampling strategy in which a single mailing is sent produces a roughly 3 percentage point higher response rate relative to a strategy sending multiple mailings concurrently to the drop point. While base-weighted distributions of gender and age differed enough to be statistically significant, there were no noteworthy differences across other demographics or across the base-weighted distributions of select key health outcomes measured by the survey. Taken together, these results provide some evidence that a “mail to one” drop point strategy is more efficient than a “mail to all” drop point strategy.