Improving the Efficiency of Outbound CATI As a Nonresponse Follow-Up Mode in Address-Based Samples: A Quasi-Experimental Evaluation of a Dynamic Adaptive Design

Abstract

This article evaluates the use of dynamic adaptive design methods to target outbound computer-assisted telephone interviewing (CATI) in the California Health Interview Survey (CHIS). CHIS is a large-scale, annual study that uses an address-based sample (ABS) with push-to-Web mailings, followed by outbound CATI follow-up for addresses with appended phone numbers. CHIS 2022 implemented a dynamic adaptive design in which predictive models were used to end dialing early for some cases. For addresses that received outbound CATI follow-up, dialing was paused after three calls. A response propensity (RP) model was applied to predict the probability that the address would respond to continued dialing, based on the outcomes of the first three calls. Low-RP addresses were permanently retired with no additional dialing, while the rest continued through six or more attempts. We use a difference-in-difference design to evaluate the effect of the adaptive design on calling effort, completion rates, and the demographic composition of respondents. We find that the adaptive design reduced the mean number of calls per sampled unit by about 14 percent (relative to a modeled no-adaptive-design counterfactual) with a minimal reduction in the completion rate and no strong evidence of changes in the prevalence of target demographics. This suggests that RP modeling can meaningfully distinguish between ABS sample units for which additional dialing is and is not productive, helping to control outbound dialing costs without compromising sample representativeness.