The effect of including an opt-out option in discrete choice experiments

Objective: to determine to what extent the inclusion of an opt-out option in a DCE may have an effect on choice behaviour and therefore might influence the attribute level estimates, the relative importance of the attributes and calculated tradeoffs. Methods: 781 Dutch Type 2 Diabetes Mellitus patients completed a questionnaire containing nine choice tasks with an optout option and nice forced choice tasks. Mixed-logit models were used to estimate the relative importance of the five lifestyle program