An experimental test of loss aversion and scale compatibility

This paper studies two important reasons why people violate procedure invariance, loss aversion and scale compatibility. The paper extends previous research on loss aversion and scale compatibility by studying loss aversion and scale compatibility simultaneously, by looking at a new decision domain, medical decision analysis, and by examining the effect of loss aversion and scale compatibility on "well-contemplated preferences." We find significant evidence both of loss aversion and scale compatibility. However, the sizes of the biases due to loss aversion and scale compatibility vary over trade-offs and most participants do not behave consistently according to loss aversion or scale compatibility. In particular, the effect of loss aversion in medical trade-offs decreases with duration. These findings are encouraging for utility measurement and prescriptive decision analysis. There appear to exist decision contexts in which the effects of loss aversion and scale compatibility can be minimized and utilities can be measured that do not suffer from these distorting factors.Decision analysis, utility theory, loss aversion, scale compatibility, health

A New Type of Preference Reversal

The classic preference reversal phenomenon arises in a comparison between a choice and a matching task. We present a new type of preference reversal which is entirely choice-based. Because choice is the basic primitive of economics, the preference reversal we observe is more troubling for economics. The preference reversal was observed in two experiments, both involving large representative samples from the Spanish population. The data were collected by professional interviewers in face-to-face interviews. Possible explanations for the preference reversal are the anticipation of disappointment and elation in risky choice and the impact of ethical considerations.Preference reversal, Choice behavior, Stochastic dominance, Disappointment and elation, Health

The Value of Health

Economic evaluations of health care can help to make better medical decisions. Decisions about life and death. Our current methods are wrong. Reality is different from what we did believe. Policy decisions based on our current tools are not at all in the best interests of patients. We, scientists, have the responsibility to bridge the gap between theory and reality. Prospect theory respects reality. Now, we have all the opportunity to reliably value health. And, these values can even be obtained free of charge: we do not have to collect additional data. We can apply prospect theory immediately. What remains is to spread the word

QALYs and HYEs: Under what conditions are they equivalent?

The paper examines what restrictions have to be imposed on the individual's preference structure for QALYs and HYEs to yield identical results. It is shown that using QALYs involves imposing three additional restrictions. Empirical evidence suggests that these restrictions cannot be expected to hold in all applications. The main problem in using HYEs appears to be practical. An alternative index is proposed, that may help to bridge the gap between QALYs and HYEs by combining to some extent the advantages of the two measures

Prospect Theory with Reference Points in the Opportunity Set

Many empirical studies have shown that preferences are reference-dependent, implying loss aversion. Because reference-dependence is a relatively new concept, there exists little theory on it. The theories that are available generally take the reference point as given and then impose the traditional assumptions such as completeness of preferences. Reference-dependence raises, however, new problems that do not occur in reference-independent theories. This paper argues that in the empirically realistic cas

Eliciting Gul’s Theory of Disappointment Aversion by the Tradeoff Method

Gul’s (1991) theory of disappointment aversion (DA) has several attractive features, being intuitive, analytically tractable, and parsimonious. In spite of this, the DA model has received little attention in practical applications, which may be partly due to the absence of a procedure to elicit the model. We show how the trade-off method, developed by Wakker and Deneffe (1996), can be used to elicit DA. Our elicitation method is parameter-free: it requires no assumption about utility and/or disappointment aversion. Quantitative tests of DA in three outcome domains, monetary gains, monetary losses, and life-years, suggest that the DA model is too parsimonious. Of the other models of disappointment aversion that have been proposed in the literature, our data are most consistent with the model of Loomes and Sugden (1986)

Standard gamble, time trade-off and rating scale: Experimental results on the ranking properties of QALYs

This paper compares the relative performance of quality adjusted life years (QALYs) based on quality weights elicited by rating scale (RS), time trade-off (TTO) and standard gamble (SG). The standard against which relative performance is assessed is individual preference elicited by direct ranking. The correlation between predicted and direct ranking is significantly higher for TTO-QALYs than for RS-QALYs and SG-QALYs. This holds both based on mean Spearman rank correlation coefficients calculated per individual and based on two social choice rules: the method of majority voting and the Borda rule. Undiscounted TTO-QALYs are more consistent with direct ranking than discounted TTO-QALY

Resolving inconsistencies in utility measurement under risk: Tests of generalizations of expected utility

This paper explores biases in the elicitation of utilities under risk and the contribution that generalizations of expected utility can make to the resolution of these biases. We used five methods to measure utilities under risk and found clear violations of expected utility. Of the theories studies, prospect theory was most consistent with our data. The main improvement of prospect theory over expected utility was in comparisons between a riskless and a risky prospect(riskless-risk methods). We observed no improvement over expected utility in comparisons between two risky prospects (risk-risk methods). An explanation why we found no improvement of prospect theory over expected utility in risk-risk methods may be that there was less overweighting of small probabilities in our study than has commonly been observed.Utility Measurement, Nonexpected Utility, Prospect Theory, Health., Leex

Time preference, the discounted utility model and health

The constant rate discounted utility model is commonly used to represent intertemporal preferences in health care program evaluations. This paper examines the appropriateness of this model, and argues that the model fails both normatively and descriptively as a representation of individual intertemporal preferences for health outcomes. Variable rate discounted utility models are more flexible, but still require restrictive assumptions and may lead to dynamically inconsistent behaviour. The paper concludes by considering two ways of incorporating individual intertemporal preferences in health care program evaluations that allow for complementarity of health outcomes in different time periods