Existing techniques for eliciting health-state valuations incorporate both strength of preferences for health states and other values such as risk aversion or time preference. This paper presents a new methodological approach that allows estimation of a set of core underlying health-state values based on responses elicited through multiple measurement techniques. A study was undertaken in which respondents completed the visual analogue (VAS) scale, time trade-off (TTO), standard gamble (SG) and person trade-off (PTO) for a range of states. By specifying flexible parametric functions to explain responses on each measurement technique, we estimated both the underlying strength of preference values for the health states in the study and the values for a set of auxiliary parameters characterising risk attitudes, discount rates, distributional concerns and scale distortion effects in the group of respondents. This study demonstrates that it is possible to understand responses on these four different measurement techniques based on a consistent set of core values. The approach presented here can provide insights into different sources of observed variation in VAS, TTO, SG and PTO responses and facilitate appropriate adjustment of valuations elicited through different methods for use in summary health measures and economic analyses.
Copyright 2003 John Wiley & Sons, Ltd.