The standard gamble method: what is being measured and how it is interpreted.
OBJECTIVE
The Standard Gamble (SG) technique is recommended for measurement of individuals' preferences under uncertainty and to express the outcome of different therapeutic choices in utility values to be used in clinical decision analysis and health program evaluation. The article alerts users of this technique to problems stemming from inappropriate interpretation of results of measurements using the SG method.


METHODS
We review different situations where the SG method is used to measure individuals' or group preferences.


RESULTS
We demonstrate inappropriate interpretation of the time dimension at the individual level; issues stemming from the aggregation of individual utility values measured using different time horizons; the potential for double counting of the time preference effect when discounting future quality-adjusted life years (QALYs); and problems associated with using the SG technique to measure temporary health states.


CONCLUSIONS
The inappropriate interpretations stem mainly either from ignoring the time dimension, which is inextricably bound to the health of the individual, or form adding assumptions, in addition to those required by von Neumann-Morgenstern (vNM) utility theory, that are not supported by empirical evidence. An alternative approach to QALYs, the healthy years equivalent (HYE), which incorporates the SG but avoids many of these problems, is described.
Gafni
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Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.
D003661:Decision Support Techniques; D006302:Health Services Research / Q000379:methods; D006304:Health Status; D006801:Humans; D008017:Life Expectancy; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D017060:Patient Satisfaction / Q000706:statistics & numerical data*; D011336:Probability; D015397:Program Evaluation / Q000379:methods*; D011788:Quality of Life; D013995:Time; D026712:Value of Life