Understanding decision-making strategies in discrete choice experiment tasks when valuing health states that include duration, a cognitive interview study with Australian adults

This study examined how participants engage with Discrete Choice Experiments (DCE) with duration tasks for valuing health states, including time preferences, and consideration of interactions between health and duration attributes. It also examined how task layout, colour, and language, particularly how dying is described, influenced decision-making. Twenty-one adults undertook online cognitive interviews while completing DCE tasks. Tasks involved health and duration attributes, with varying durations (weeks to 20 years) and split triplet designs in which respondents first choose between health states with the same duration and then between one of those health states and either full health for a shorter duration or immediate death. Data were analysed using Framework Analysis with iterative coding and a final thematic framework. Participants showed willingness to trade life-years for better health, evidence of Maximum Endurable Time, and high value placed on final weeks for closure and goodbyes. Some participants interacted health attributes with duration where duration differed, while others did not. No additional clear evidence of discounting future time emerged. Some participants had emotive reactions to specific phrasing, underscoring the impact of inconsistent wording between choices. Overlapping domains, particularly combined with the use of colour, made tasks easier but sometimes led to ignored domains when duration varied. Participants struggled with hypothetical scenarios and unfamiliar health attributes. Considering the complexity of decision-making and the influence of framing, presentation and language can inform design and modelling choices for DCE with duration studies. Little is known about individuals’ decision-making when answering DCE with duration questions, particularly whether they adopt a non-zero-time preference or consider interactions between the duration and attributes in a choice set. In cognitive interviews with adults we found that choices were influenced by Maximal Endurable Time and the importance of the final weeks before death. Participants did not articulate other clear evidence of discounting future time. Language, colour, and holding attributes constant within choice sets can affect thought-processes and this should be considered during DCE design. While overlap safely simplifies choice tasks with equal durations, it can prevent multiplicative reasoning when durations differ.