Evaluating a double list experiment to measure the population proportion of people who have attempted a self-managed abortion in the United States: analysis of a nationally representative cross-sectional survey in 2017

Abstract Objective: To explore the performance of the list experiment as a tool to reduce underreporting in estimation of self-managed abortion attempts in the United States. Study Design: We analyzed data from a 2017 nationally representative survey of self-identified females aged 18 to 49 in the United States recruited via Ipsos’ KnowledgePanel (n = 6897). We estimated the proportion of respondents who had ever attempted a self-managed abortion using a direct question as compared to a double list experiment. Results: We estimated that 8.2% (95% CI, 6.5, 9.9) had ever attempted to self-manage an abortion based on responses to the double list experiment—nearly three times the 2.7% (95% CI, 2.2, 3.4) estimated via the direct question. However, one of the two list sets performed inconsistently overall, and particularly among respondents who took the survey in Spanish. Conclusion: Future research that aims to measure self-managed abortion attempts in a hostile political context can consider the list experiment as a tool to reduce under-reporting, with additional qualitative and cognitive work needed to improve list performance.