Handling Drop Points in Surveys

Survey designers need to consider what categories of addresses to include as part of address frames, often defined by “delivery type,” e.g., residential, business, PO BOX, and others. Drop points can be a particularly challenging category because they are non-differentiated multi-unit addresses. Specifying a selected housing unit from the computerized delivery sequence file (CDS) is thus not directly possible, challenging common processes associated with address-based sample (ABS) designs, including vendor matching and demographic appends in addition to basic data collection. Our paper first reviews solutions that have been considered in the research industry to include drop points in multi-mode ABS designs over the past decade. We then demonstrate a variety of imputation methods utilized at NORC to assist in assigning unit labels to drop point addresses. We conclude by describing how each imputation method has coverage and representation advantages over previous approaches.