Transitioning to a Mixed-Mode Study Design in a National Household Panel Study: Effects on Fieldwork Outcomes, Sample Composition and Costs.

The U.S. Panel Study of Income Dynamics (PSID) made a planned transition to a web-first mixed-mode data collection design in 2021 (web and computer-assisted telephone interviewing [CATI]), following nearly five decades of collecting data primarily using CATI with professional interviewers. To evaluate potential effects of mode on fieldwork outcomes, two sequential mixed-mode protocols were introduced using an experimental design. One protocol randomized sample families to a "web-first" treatment, which encouraged response through an online interview, followed by an offer of telephone to complete the interview; a second protocol randomized sample families to a "CATI-first" treatment until the last phase of fieldwork when the option to complete a web interview was offered. This paper examines the comparative effects of the two protocols on fieldwork outcomes, including response rates, interviewer contact attempts, fieldwork duration, and cost. Comparisons are also made with fieldwork outcomes and characteristics of non-responding sample members from the prior-wave when a traditional telephone design was used. We found that the web-first design compared to the CATI-first design led to comparably high response rates, and faster interview completion with lower effort and cost. With some notable exceptions, compared to the prior wave, the mixed-mode design reduced effort and had generally similar patterns of non-response among key respondent subgroups. The results provide new empirical evidence on the effects of mixing modes on fieldwork outcomes and costs and contribute to the small body of experimental evidence on the use of mixed-mode designs in household panel studies.