Reducing underreporting of abortion in surveys: Results from two test applications of the list experiment method in Malawi and Senegal

BACKGROUND: Accurately measuring abortion incidence poses many challenges. The list experiment is a method designed to increase the reporting of sensitive or stigmatized behaviors in surveys, but has only recently been applied to the measurement of abortion. To further test the utility of the list experiment for measuring abortion incidence, we conducted list experiments in two countries, over two time periods. MATERIALS AND METHODS: The list experiment is an indirect method of measuring sensitive experiences that protects respondent confidentiality by hiding individual responses to a binary sensitive item (i.e., abortion) by combining this response with answers to other non-sensitive binary control items. Respondents report the number of list items that apply to them, not which ones. We conducted a list experiment to measure cumulative lifetime incidence of abortion in Malawi, and separately to measure cumulative five-year incidence of abortion in Senegal, among cisgender women of reproductive age. RESULTS: Among 810 eligible respondents in Malawi, list experiment results estimated a cumulative lifetime incidence of abortion of 0.9% (95%CI: 0.0, 7.6). Among 1016 eligible respondents in Senegal, list experiment estimates indicated a cumulative five-year incidence of abortion of 2.8% (95%CI: 0.0, 10.4) which, while lower than anticipated, is seven times the proportion estimated from a direct question on abortion (0.4%). CONCLUSIONS: Two test applications of the list experiment to measure abortion experiences in Malawi and Senegal likely underestimated abortion incidence. Future efforts should include context-specific formative qualitative research for the development and selection of list items, enumerator training, and method delivery to assess if and how these changes can improve method performance.