An Evaluation of Incentive Experiments in a Two-Phase Address-Based Sample Mail Survey

Abstract

Address-based sampling (ABS) with a two-phase data collection approach has emerged as a promising alternative to random digit dial (RDD) surveys for studying specific subpopulations in the United States. In 2011, the National Household Education Surveys Program Field Test used a two-phase ABS design with a postal or mail screener to identify households with eligible children and a mail topical questionnaire administered to parents of sampled children to collect measures of interest. Experiments with prepaid cash incentives and special mail delivery methods were applied in both phases. For the screener, sampled addresses were randomly designated to receive either $2 or $5 in the initial mailing. During the topical phase, incentives (ranging from $0 to $20) and delivery methods (First Class Mail or Priority Mail) were assigned randomly but depended on how quickly the household had responded to the screener. The paper first evaluates the effects of incentives on response rates, and then examines incentive levels for attracting the hard-to-reach groups and improving sample composition. The impact of incentive on data collection cost is also examined.