Additive conjoint measurement for multiattribute utility

This paper shows that multiattribute utility can be simplified by methods from additive conjoint measurement. Given additive conjoint measurability under certainty, axiomatizations can be simplified, and implementation and reliability of elicitation can be improved. This also contributes to the discussion of (non-)identity of utility under certainty and under uncertainty. Examples are obtained where two such utilities must be different on normative grounds. In establishing this difference, a classical meaningfulness pitfall is to be avoided. Finally, additive conjoint measurement can be used to refine the measurement of QALYs (quality adjusted life years) in medical decision making; this is demonstrated by an experiment.