Risk Preferences Are Not Time Preferences (original) (raw)
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I ntertemporal decision making under risk involves two dimensions: time preferences and risk preferences. This paper focuses on the impact of time on risk preferences, independent of the intertemporal trade-off of outcomes, i.e., time preferences. It reports the results of an experimental study that examines how delayed resolution and payment of risky options influence individual choice. We used a simple experimental design based on the comparison of two-outcome monetary lotteries with the same delay. Raw data clearly reveal that subjects become more risk tolerant for delayed lotteries. Assuming a prospect theory-like model under risk, we analyze the impact of time on utility and decision weights, independent of time preferences. We show that the subjective treatment of outcomes (i.e., utility) is not significantly affected by time. In fact, the impact of time is completely absorbed by the probability weighting function. The effect of time on risk preferences was found to generate probabilistic optimism resulting in a higher risk tolerance for delayed lotteries.
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Some decisions involve uncertain outcomes. For example, selecting an entrée at a restaurant entails uncertainty about how delicious each menu option would be. Other decisions involve delayed outcomes. For example, initiating an exercise program entails a delay until the positive results of exercise are observed. Both decision making under uncertainty and intertemporal choice have been the topic of much research. In the present article, we analyze potential parallels between these two types of choices.
Risk Preferences Are Not Time Preferences: Reply
American Economic Review, 2015
Can the well-known experimental phenomenon of present-bias in intertemporal choice be confounded with the risks associated with receiving payment? Can measurements of risk preferences be used to represent desires for smoothness in intertemporal payments? In our two 2012 papers in this journal we explored these two questions and found the answer to the first to be yes and the second to be no. We feel the three papers inspired by our work and published here underscore these arguments and point to interesting new possibilities for modeling and measuring risk over time. (JEL C91, D81, D91)