Methods for assessing relative importance in preference based outcome measures.

This paper reviews issues relevant to preference assessment for utility based measures of health-related quality of life. Cost/utility studies require a common measurement of health outcome, such as the quality adjusted life year (QALY). A key element in the QALY methodology is the measure of preference that estimates subjective health quality. Economists and psychologists differ on their preferred approach to preference measurement. Economists rely on utility assessment methods that formally consider economic trades. These methods include the standard gamble, time-trade off and person trade-off. However, some evidence suggests that many of the assumptions that underlie economic measurements of choice are open to challenge because human information processors do poorly at integrating complex probability information when making decisions that involve risk. Further, economic analysis assumes that choices accurately correspond to the way rational humans use information. Psychology experiments suggest that methods commonly used for economic analysis do not represent the underlying true preference continuum and some evidence supports the use of simple rating scales. More recent research by economists attempts integrated cognitive models, while contemporary research by psychologists considers economic models of choice. The review also suggests that difference in preference between different social groups tends to be small.