Understanding the Two Components of Risk Attitudes: An Experimental Analysis

Economics and management science share the tradition of ordering risk aversion by ï¬tting the best expected utility (EU) model with a certain utility function to individual data, and then using the utility curvature for each individual as the sole index of risk attitude. (Cumulative) Prospect theory (CPT) has demonstrated various empirical deï¬ciencies of EU and introduced the weighting of probabilities as an additional component to capture risk attitude. However, if utility curvature and probability weighting were strongly correlated, the utility curvature in EU alone, while not properly describing risky behavior in general, would still capture most of the variance regarding degrees of risk aversion. This study shows, however, that such a strong correlation does not exist. Though, most individuals exhibit concave utility and convex probability weighting, the two components show no correlation. Thus neglecting one component entails a loss.risk attitudes, cumulative prospect theory, experimental study

Understanding the Two Components of Risk Attitudes: An Experimental Analysis

Cumulative Prospect Theory (PT) introduced the weighting of probabilities as an additional component to capture risk attitudes. However, this addition would be a less significant challenge to expected utility theory (EU) if utility curvature and probability weighting showed strong positive correlation. In that case the utility curvature in EU alone, while not properly describing risky behavior in general, would still capture most of the variance of individual risk aversion. This study provides experimental evidence that such a strong and positive correlation does not exist. Although most individuals exhibit concave utility and convex probability weighting, the two components show no strong positive correlation.risk attitudes, cumulative prospect theory, experimental study

The Behavioural Components of Risk Aversion

The risk premium is affected by loss aversion and probability distortions as well as utility curvature. We introduce two variants - the total risk premium relative to objective expected value, and the subjective risk premium relative to perceived expected value. Approximate solutions for each provide analogies to the Pratt-Arrow coefficient of risk aversion (showing how risk attitude depends on each behavioural component), and sufficient conditions for risk aversion. Earlier results of Levy and Levy (2002) which examined decision weights in isolation are revised and extended to show how the curvature and loss aversion conditions are affected by probabilitydistortions

Heterogeneity in Risky Choice Behaviour in a Broad Population

We analyse risk preferences using an experiment with real incentives in a representative sample of 1,422 Dutch respondents. Our econometric model incorporates four structural parameters that vary with observed and unobserved characteristics: Utility curvature, loss aversion, preferences towards the timing of uncertainty resolution, and the propensity to choose randomly rather than on the basis of preferences. We find that all four parameters contribute to explaining choice behaviour. The structural parameters are significantly associated with socio-economic variables, but it is essential to incorporate unobserved heterogeneity in each of them to match the rich variety of choice patterns in the data.risk aversion, loss aversion, uncertainty resolution, field experiments

Heterogeneity in Risky Choice Behavior in a Broad Population

We analyse risk preferences using an experiment with real incentives in a representative sample of 1,422 Dutch respondents. Our econometric model incorporates four structural parameters that vary with observed and unobserved characteristics: Utility curvature, loss aversion, preferences towards the timing of uncertainty resolution, and the propensity to choose randomly rather than on the basis of preferences. We find that all four parameters contribute to explaining choice behaviour. The structural parameters are significantly associated with socio-economic variables, but it is essential to incorporate unobserved heterogeneity in each of them to match the rich variety of choice patterns in the data.risk aversion;loss aversion;uncertainty resolution;field experiments

Responsibility Effects in Decision Making under Risk

We systematically explore decision situations in which a decision maker bears responsibility for somebody else's outcomes as well as for her own in situations of payoff equality. In the gain domain we confirm the intuition that being responsible for somebody else's payoffs increases risk aversion. This is however not attributable to a 'cautious shift' as often thought. Indeed, looking at risk attitudes in the loss domain, we find an increase in risk seeking under responsibility. This raises issues about the nature of various decision biases under risk, and to what extent changed behavior under responsibility may depend on a social norm of caution in situations of responsibility versus naive corrections from perceived biases. To further explore this issue, we designed a second experiment to explore risk-taking behavior for gain prospects offering very small or very large probabilities of winning. For large probabilities, we find increased risk aversion, thus confirming our earlier finding. For small probabilities however, we find an increase of risk seeking under conditions of responsibility. The latter finding thus discredits hypotheses of a social rule dictating caution under responsibility, and can be explained through flexible self-correction models predicting an accentuation of the fourfold pattern of risk attitudes predicted by prospect theory. An additional accountability mechanism does not change risk behavior, except for mixed prospects, in which it reduces loss aversion. This indicates that loss aversion is of a fundamentally different nature than probability weighting or utility curvature. Implications for debiasing are discussed

A Parametric Analysis of Prospect Theory's Functionals for the General Population

This paper presents the results of an experiment that completely measures the utility function and probability weighting function for different positive and negative monetary outcomes, using a representative sample of N = 1935 from the general public. The results confirm earlier findings in the lab, suggesting that utility is less pronounced than what is found in classical measurements where expected utility is assumed. Utility for losses is found to be convex, consistent with diminishing sensitivity, and the obtained loss aversion coefficient of 1.6 is moderate but in agreement with contemporary evidence. The estimated probability weighing functions have an inverse-S shape and they imply pessimism in both domains. These results show that probability weighting is also an important phenomenon in the general population. Women and lower educated individuals are found to be more risk averse, in agreement with common findings. Unlike previous studies that ascribed gender differences in risk attitudes solely to differences in the degree utility curvature, however, our results show that this finding is primarily driven by loss aversion and, for women, also by a more pessimistic psychological response towards the probability of obtaining the best possible outcome.loss aversion, utility for gains and losses, prospect theory, subjective probability weighting

A test of the predictive validity of non-linear QALY models using time trade-off utilities

This paper presents a test of the predictive validity of various classes of QALY models (i.e., linear, power and exponential models). We first estimated TTO utilities for 43 EQ-5D chronic health states and next these states were embedded in health profiles. The chronic TTO utilities were then used to predict the responses to TTO questions with health profiles. We find that the power QALY model clearly outperforms linear and exponential QALY models. Optimal power coefficient is 0.65. Our results suggest that TTO-based QALY calculations may be biased. This bias can be avoided using a power QALY model.Cost-utility analysis, QALYs, power QALY model, predictive validity, time tradeoff, Leex

A Parametric Analysis of Prospect Theory's Functionals for the General Population

This paper presents the results of an experiment that completely measures the utility function and probability weighting function for different positive and negative monetary outcomes, using a representative sample of N = 1935 from the general public. The results confirm earlier findings in the lab, suggesting that utility is less pronounced than what is found in classical measurements where expected utility is assumed. Utility for losses is found to be convex, consistent with diminishing sensitivity, and the obtained loss aversion coefficient of 1.6 is moderate but in agreement with contemporary evidence. The estimated probability weighing functions have an inverse-S shape and they imply pessimism in both domains. These results show that probability weighting is also an important phenomenon in the general population. Women and lower educated individuals are found to be more risk averse, in agreement with common findings. Unlike previous studies that ascribed gender differences in risk attitudes solely to differences in the degree utility curvature, however, our results show that this finding is primarily driven by loss aversion and, for women, also by a more pessimistic psychological response towards the probability of obtaining the best possible outcome.prospect theory, utility for gains and losses, loss aversion, subjective probability weighting

Debiasing EQ-5D Tariffs. New estimations of the spanish EQ-5D value set under nonexpected utility

Este proyecto tiene como objetivo estimar las utilidades asociadas a los estados de salud definidos mediante el sistema EuroQol-5D a partir de la medición directa de las preferencias de una muestra de la población andaluza. Los valores obtenidos serán susceptibles de ser utilizados en el marco de estudios de evaluación económica de políticas sanitarias (análisis coste-utilidad) realizados en la comunidad andaluza y en el conjunto del estado. Para la valoración directa de un subconjunto de estados de salud se realizará una encuesta personal asistida por ordenador a una muestra representativa por sexo y cuotas de edad de la población española, extraída de la población residente en Andalucía. Los métodos que se aplicarán para obtener las preferencias y calcular las utilidades tratarán de corregir algunos de los sesgos que pueden afectar a las estimaciones existentes. Así, se adoptarán enfoques teóricos alternativos a los habitualmente empleados que permitirán relajar algunos de los supuestos que han sido puestos en cuestión a la luz de la evidencia empírica, como es el caso de la linealidad de la función de utilidad del tiempo de vida, la validez descriptiva de la teoría de la utilidad esperada o la separabilidad multiplicativa de las preferencias por cantidad y calidad de vida.EQ-5D, social tariff, utility curvature, probability weighting, rank-dependent utility, time trade-off, value lottery equivalence, certainlty equivalence