Impact of Mode Switching on Nonresponse and Bias in a Multimode Longitudinal Study of Young Adults

Abstract

Young adults are generally hard to survey, presenting researchers with numerous difficulties. They are hard to locate and contact due to high mobility. They are hard to persuade and exhibit high levels of resistance to survey participation. As a result, they pose a greater challenge for longitudinal surveys. This paper explores the role of mode of data collection in young adults’ decisions to stay in a longitudinal panel. We draw on data from the National Young Adult Health Study (NYAHS). NYAHS is a longitudinal study (three annual waves and 2 brief between-wave follow-up surveys) of adults aged 18-34 initially recruited in 2019 through RDD sampling of cell phone numbers nationwide. Once screened in, one-third of young adults were randomly assigned to continue all rounds of interviews by telephone (“single telephone mode” condition). One-third were assigned to alternate between telephone and web for the later interviews (“mixed mode” condition). The last third was asked to complete subsequent interviews online (“single web mode” condition). We examined the impact of mode switching on young adults’ likelihood of participating in later surveys and on nonresponse bias in key survey outcomes. We found that switching young adults from telephone to web had an immediate negative effect on their likelihood of participating in that web survey, but it did not have a continued negative effect. Switching them from web to telephone increased response rates and reduced nonresponse bias.  The findings have important practical implications on how to survey young adults.