“I was trying to do the maths”

Abstract

BackgroundRisk is increasingly used as an attribute in discrete choice experiments (DCEs). However, risk and probabilities are complex concepts that can be open to misinterpretation, potentially undermining the robustness of DCEs as a valuation method. This study aimed to understand how respondents made benefit-risk trade-offs in a DCE and if these were affected by the communication of the risk attributes.MethodsFemale members of the public were recruited via local advertisements to participate in think-aloud interviews when completing a DCE eliciting their preferences for a hypothetical breast screening programme described by three attributes: probability of detecting a cancer; risk of unnecessary follow-up; and cost of screening. Women were randomised to receive risk information as either (1) percentages or (2) percentages and icon arrays. Interviews were digitally recorded then transcribed to generate qualitative data for thematic analysis.ResultsNineteen women completed the interviews (icon arrays n=9; percentages n=10). Analysis revealed four key themes where women made references to (1) the nature of the task; (2) their feelings; (3) their experiences, for instance making analogies to similar risks; and (4) economic phenomena such as opportunity costs and discounting.ConclusionMost women completed the DCE in line with economic theory; however, violations were identified. Women appeared to visualise risk whether they received icon arrays or percentages only. Providing clear instructions and graphics to aid interpretation of risk and qualitative piloting to verify understanding is recommended. Further investigation is required to determine if the process of verbalising thoughts changes the behaviour of respondents.