The use of composite time trade-off and discrete choice experiment methods for the valuation of the Short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS): a think-aloud study.

PURPOSE: To identify patterns and problems in completing composite time trade-off (C-TTO) and discrete choice experiment (DCE) exercises for the valuation of the Short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS) to inform the optimisation of a valuation protocol. METHODS: Fourteen cognitive interviews were conducted in the UK using concurrent and retrospective think-aloud and probing techniques. Each participant completed 8 C-TTO tasks and 8 DCE tasks within a computer-assisted personal interview setting. Verbal information was transcribed verbatim. Axial coding and thematic analysis were used to organise the qualitative data and identify patterns and problems with the completion of tasks. RESULTS: While participants found the tasks generally manageable, five broad themes emerged to explain and optimise the response to the tasks. (1) Format and structure: attention to the design of practice examples, instructions, and layout were needed. (2) Items and levels: underlying relationships were discovered across different combinations of levels of SWEMWBS items. (3) Decision heuristics: participants engaged in diverse strategies to assist trade-off decisions. (4) Valuation feasibility: certain states were difficult to imagine, compare and quantify. (5) Valuation outcome: the data quality was affected by participants' discriminatory ability across states and their time trade-off decisions. CONCLUSION: The interviews contributed insights regarding the robustness of the proposed methods. The application of C-TTO and DCE valuation techniques was practical and suitable for capturing individual attitudes towards different mental well-being scenarios. A modified protocol informed by the results is being tested in a larger sample across the UK.