Healthy years equivalents versus time trade-off. Ambiguity on certainty and uncertainty.

Preference assessment literature has debated the equivalence of the healthy years equivalents (HYE) and time trade-off (TTO) methods. The central issue is whether the HYE measures preferences under uncertainty. This work shows that the two stages of the HYE first add and then remove the element of uncertainty so that ultimately the technique doses not measure preferences under uncertainty. This makes the HYE, at best, a cumbersome equivalent of the TTO.