However, the National Centre for Clinical Excellence (NICE) recommended that quality of life measured by a valid preference-based measure of health should be incorporated into the outcome measure of effectiveness, to so called quality adjusted life years (QALYs), in analysis of an medical intervention [ 15].
This result has implications for the mink welfare debate and also for the design of valid preference experiments.
As the deletion of such responses has recently been cautioned against due in part to the shortcomings of the tests to truly detect irrationality and consequent removal of potentially valid preference responses, and considering that the existence of such preferences can be seen to be consistent with random utility theory [ 24, 33], all responses were included in the final model.
Although the results show apparent non-attendance to some attributes (e.g., cash payments), qualitative debriefings suggest that respondents infact do expect relatively low or no utility from the given attributes and hence have theoretically valid preferences.
Improved understanding of how the design and presentation of health state descriptions affect responses will be useful to eliciting valid preferences for incorporation into decision making.
Finally, and after the aspects of each individual vignette had been ranked, respondents rank ordered the vignettes themselves, thereby expressing a preference for, say, surgery, public health medicine, psychiatry, or clinical research, preferences expressed after deep and active processing of specific aspects of each speciality, making them more likely to be valid preferences.
So doing would promote the engagement of the participants and thereby be conducive to a valid set of preference data.
Where information is limited or when one attribute actually is considerably more important than all others, non-compensatory responses can be a valid expression of preferences.
Unfortunately, as in traditional DCEs, it usually is impossible to determine whether non-compensatory responses are a valid expression of preferences or a simplifying heuristic designed to avoid the effort of evaluating trade-offs.
Therefore, the collection of preference data that can measure preferences and differences in preferences in a valid way using DCEs and DCEBWS is of decisive importance for health economics and health services research.
