Exploring Differences between TTO and DCE in the Valuation of Health States.

There is recent interest in using discrete choice experiments (DCEs) to derive health state utility values, and results can differ from time tradeoff (TTO). Clearly, DCE is "choice based," whereas TTO is generally considered a "matching" task. We explore whether procedural adaptations to the TTO, which make the method more closely resemble a DCE, make TTO and choice converge. In particular, we test whether making the matching procedure in TTO less "transparent" to the respondent reduces disparities between TTO and DCE. We designed an interactive survey that was hosted on the Internet, and 2022 interviews were achieved in the United Kingdom in a representative sample of the population. We found a marked divergence between TTO and DCE, but this was not related to the "transparency" of the TTO procedure. We conclude that a difference in the error structure between TTO and choice and that factors other than differences in utility are affecting choices is driving the divergence. The latter has fundamental implications for the way choice data are analyzed and interpreted.