Time trade-off: one methodology, different methods

Abstract

There is no scientific consensus on the optimal specification of the time trade-off (TTO) task. As a consequence, studies using TTO to value health states may share the core element of trading length of life for quality of life, but can differ considerably on many other elements. While this pluriformity in specifications advances the understanding of TTO from a methodological point of view, it also results in incomparable health state values. Health state values are applied in health technology assessments, and in that context comparability of information is desired. In this article, we discuss several alternative specifications of TTO presented in the literature. The defining elements of these specifications are identified as being either methodological, procedural or analytical in nature. Where possible, it is indicated how these elements affect health state values (i.e., upward or downward). Finally, a checklist for TTO studies is presented, which incorporates a list of choices to be made by researchers who wish to perform a TTO task. Such a checklist enables other researchers to align methodologies in order to enhance the comparability of health state values.

Do Chinese have similar health-state preferences? A comparison of mainland Chinese and Singaporean Chinese

“…Moreover, those studies used data collected from independent studies conducted at different times by different investigators. In contrast, data used in our study was collected by the same investigators using exactly the same study protocol, thus ruling out the possibility that the observed difference in TTO values was due to the use of different valuation procedures [29].…”

“Naming and Framing”: The Impact of Labeling on Health State Values for Multiple Sclerosis

“…Concerns have been raised about whether TTO tasks may pose too high a cognitive burden for online administration 25 . While recent evaluations of internet TTO have produced mixed results 26-28 , the nature of the preference data elicited here, alongside respondents' selfreported task comprehension, suggest that the TTO technique can be administered successfully online.…”

Influenced from the start: anchoring bias in time trade-off valuations

“…Additional manipulations could increase the effect of the starting point: For example, different lengths of lead time, changing the increment size of tradable time, allowing negative starting points, increasing the visible length of the TTO bars, or offering health states with different durations would all potentially influence elicited values [22–24]. …”