A Theory of Measurable Ambiguity

该项目开发并分析了一种新的不确定条件下的选择模型。不确定情况下的标准理性选择模型是冯·诺伊曼·摩根斯坦期望效用模型。主观期望不确定效用(SEUU)模型是简单的，也适用于分析模糊情况下人们是如何做出决策的，该模型有一种新的事件评估准则，称为半概率复杂性，将行为归结为双彩票，并根据期望效用准则对这些赌博进行评估。这个框架可以很容易地用于分析不明确的事件和不确定的后果。该模型的基本特征是，在一个模棱两可的事件上下注会产生一场不确定的赌博。个体可能更喜欢这种模棱两可的赌博，而不是押注于一个平淡无奇的事件，这取决于这两个事件的可能性有多大，它们有多模棱两可，以及他/她对不确定性的态度。这项研究为新理论提供了一个公理基础，开发和分析了适当的不确定性和风险厌恶衡量标准，并将它们与模棱两可的情况的性质联系起来，并确定了对该模型进行实证检验的方法。这项研究将产生更广泛的影响，因为一个易于处理的模棱两可的模型将适用于宏观经济学和金融经济学中的许多研究和政策问题。

The project develops and analyzes a new model of choice under uncertainty. The standard rational choice model for uncertain situations is the von Neumann Morgenstern Expected Utility model. While economists and other social scientists have used this model as the foundation for a great deal of research, the model does not do a good job of predicting how individuals make decisions in ambiguous situations. The Subjective Expected Uncertain Utility (SEUU) model is simple and is also suitable for analyzing how people make decisions under ambiguity.The model has a novel event-assessment criterion called semiprobabilistic sophistication, reduces acts into gambles called bilotteries, and evaluates these gambles according to an expected utility criterion. This framework can easily be used to analyze ambiguous events and uncertain consequences. The basic feature of the model is that betting on an ambiguous event yields an uncertain gamble. The individual may or may not prefer such an ambiguous gamble to a bet on an unabiguous event depending on how likely the two evets are, how ambiguous they are, and his/her attitude towards uncertainty.The research provides an axiomatic foundation for the new theory, develops and analyses appropriate measures of uncertainty and risk aversion and relates them to properties of ambiguous situations, and identifies ways to empirically test this model.This research will have broader impact because a tractable model of ambiguity will be applicable to many research and policy questions in macroeconomics and financial economics.