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

A new preference reversal in health utility measurement

A central assumption in health utility measurement is that preferences are invariant to the elicitation method that is used. This assumptioin is challenged by preferences reversals. Previous studies have observed prefrence resersals between choise and matching tasks and between choise and ranking tasks. We present a new preference reversal that entirely choise-based. Because choise is the basic primitive of economics and utility theory, this preference reversal is more fundamental and troubling. The preference reversal was observed in two studies regarding health states after stroke. Both studies involved large representative samples from the Spanish population, interwied professionally and face-to-face. Possible explanations for the preference reversal are the anticipation of disappointment and elation is risky choise anda the impact of ethical co0nsiderations about the value of live.Health utility measurement, preference reversal, choice behavior

Sequencing Anomalies in Choice Experiments

This paper investigates whether responses to choice experiments (CEs) are subject to sequencing anomalies. While previous research has focussed on the possibility that such anomalies relate to position in the sequence of choice tasks, our research reveals that the particular sequence of tasks matters. Using a novel experimental design that allows us to test our hypotheses using robust nonparametric statistics, we observe sequencing anomalies in CE data similar to those recorded in the dichotomous choice contingent valuation literature. Those sequencing effects operate in both price and commodity dimensions and are observed to compound over a series of choice tasks. Our findings cast serious doubt on the current practice of asking each respondent to undertake several choice tasks in a CE whilst treating each response as an independent observation on that individual’s preferences.Choice experiments; sequencing anomalies; ordering effects; dichotomous choice contingent valuation; non-parametric testing.

THE LEAD TIME TRADE-OFF: THE CASE OF HEALTH STATES BETTER THAN DEATH

The Lead Time Trade-Off (L-TTO) is a variant of the TTO method that tries to overcome some of the problems of the most widely used method (Torrance, 1986) for health states worse than death (SWD). Theoretically, the new method reduces the problems that have been detected when researchers have elicited preferences for SWD. However, several questions remain to be clarified. One of them is the influence of this new method for states better than death (SBD). In this paper we try to shed some light on this issue using a split sample design (n=500). One subsample (n=188) was interviewed using L-TTO and the rest using the traditional TTO (T-TTO). Our results show that the L-TTO produces utilities that are consistently higher than the T-TTO for SBD. Furthermore, the higher the severity the higher the difference between both methods. Another finding is that the L-TTO seems to produce a lower number of SWD. This effect seems to be concentrated in the most severe health states. This implies a violation of additive separability, one of the cornerstones of the QALY model. Our data show that the L-TTO may be different from the T-TTO in more respects than those that were originally intended.Lead Time Trade-Off, QALYs, Discounting, Additive Independece

THE LEAD TIME TRADE-OFF: THE CASE OF HEALTH STATES BETTER THAN DEATH

The Lead Time Trade-Off (L-TTO) is a variant of the TTO method that tries to overcome some of the problems of the most widely used method (Torrance, 1986) for health states worse than death (SWD). Theoretically, the new method reduces the problems that have been detected when researchers have elicited preferences for SWD. However, several questions remain to be clarified. One of them is the influence of this new method for states better than death (SBD). In this paper we try to shed some light on this issue using a split sample design (n=500). One subsample (n=188) was interviewed using L-TTO and the rest using the traditional TTO (T-TTO). Our results show that the L-TTO produces utilities that are consistently higher than the T-TTO for SBD. Furthermore, the higher the severity the higher the difference between both methods. Another finding is that the L-TTO seems to produce a lower number of SWD. This effect seems to be concentrated in the most severe health states. This implies a violation of additive separability, one of the cornerstones of the QALY model. Our data show that the L-TTO may be different from the T-TTO in more respects than those that were originally intended.Lead Time Trade-Off, QALYs, Discounting, Additive Independece

Trying to estimate a monetary value for the QALY

In this paper we study the possibility of estimating a monetary value for the QALY. Using two different surveys of the Spanish population (n=900), we try to establish whether willingness to pay (WTP) is (almost) proportional to the health gains measured in QALYs. We also explore whether subjects’ responses are prone to any biases. We find that the monetary value of the QALY is higher the smaller the health gain, pointing to insensitivity in WTP. We also find two clear biases. One is the existence of sequencing effects. The other is the insensitivity of WTP to the duration of the period of payment. All these effects translate into a large variation in estimates of the monetary value of the QALY. We conclude that in order to be able to obtain consistent and stable estimates, we should try to understand better the causes of these problems with a view to developing ways of mitigating them.QALYs, willingness to pay, biases.

Testing the predective validity of the time trade-off and the Stardard Gamble

This paper tests the consistency of health utility measurements with individual preferences. We compare three methods, the time trade-off, the standard gamble and a version of the standard gamble that corrects for the deviations from expected utility modelled by prospect theory. Individual preferences are measured both through a ranking task and through a choice task. In decisions involving no risk the time trade-off is most consistent with people’s preferences with the standard gamble a close second. In decisions involving risk the corrected standard gamble is most consistent with people’s preferences. Our data do not support the common assumption in health economics that utility is transferable across decision contexts.Health utility measurement, QALYs,stardard gamble, time trade-off, prospect theory.

Valuing qalys at the end of life

There have been changes in the way that NICE evaluates medical treatments for patients who are in the last stages of their lives. If medicines fulfil some criteria to be considered “end of life” NICE considers if QALYs gained under these circumstances should receive an extra weight. In this paper we provide evidence about the social support that this policy may have. We present the result of three surveys conducted in the Spanish general population (n=813). Survey 1 compared increases in life expectancy for patients at the end of their lives with health gains from temporary health problems. Survey 2 compared health gains for temporary health problems with health gains from end of life palliative care. Survey 3 compared increases in life expectancy with palliative care in both cases for end of life patients. Preferences were elicited with Person Trade-Off and Willingness to pay techniques. Our results suggest that QALYs for end of life treatments have a higher social value than for temporary health problems. However, we also find that people discriminate between different ways of health gains within End of Life treatment. People seem to attach a greater weight to palliative care than to life extension.QALY weights, end of life, palliative care, life extension