Option price without expected utility

We consider the meaning of the option price, commonly acknowledged as the preferred ex ante welfare measure, in the rank-dependent expected utility (RDEU) framework. The importance of this pertains to performing benefit-cost analysis when RDEU maximizers are prevalent in society.     

The subjective expected utility hypothesis and revealed preference

Summary A choice behavior of a decision maker is said to satisfy the subjective expected utility hypothesis if there exist a utility and a subjective probability such that a decision maker chooses acts with the highest expected utility. We present a revealed preference characterization of choice behavior that is consistent with the subjective expected utility hypothesis. Our result applies to any state space and compact sets of prizes and observations (either finite or infinite).     

Subjective ambiguity, expected utility and Choquet expected utility

Summary. Using the Savage set up, this paper provides a simple axiomatization of the Choquet Expected Utility model where the capacity is an inner measure. Two attractive features of the model are its specificity and the transparency of its axioms. The key axiom states that the decision-maker uses unambiguous acts to approximate ambiguous ones. In addition, the notion of ‘ambiguity’ is subjective and derived from preferences. Received: March 23, 2000; revised version: April 24, 2001     

Reference-dependent subjective expected utility

A reference-dependent generalisation of subjective expected utility theory is presented. In this theory, preferences between acts depend both on final outcomes and on reference points (which may be uncertain acts). It is characterised by a set of axioms in a Savage-style framework. A restricted form of the theory separates attitudes to end states (encoded in a ‘satisfaction function’) from attitudes to gains and losses of satisfaction. Given weak additional assumptions, the restricted theory excludes cycles of choice, explains observed disparities between willingness-to-pay and willingness-to-accept valuations of lotteries, and predicts preference reversal.     

Neurally reconstructing expected utility

While the concept of “expected utility” informs many theories of decision making, little is known about whether and how the human brain might compute this quantity. This article reviews a series of functional magnetic resonance imaging (FMRI) experiments designed to localize brain regions that respond in anticipation of increasing amounts of monetary incentives. These studies collectively suggest that anticipation of increasing monetary gains activates a subcortical region of the ventral striatum in a magnitude-proportional manner. This ventral striatal activation is not evident during anticipation of losses. Actual gain outcomes instead activate a region of the mesial prefrontal cortex. During anticipation of gain, ventral striatal activation is accompanied by feelings characterized by increasing arousal and positive valence. These findings affirm the role of emotion in the anticipation of incentives, and may provide an initial step towards a neural reconstruction of expected utility.     

Subjective recursive expected utility

We axiomatize a subjective version of the recursive expected utility model. This development extends the seminal results of Kreps and Porteus (Econometrica 46:185–200 (1978)) to a subjective framework and provides foundations that are easy to relate to axioms familiar from timeless models of decision making under uncertainty. Our analysis also clarifies what is needed in going from a represention that applies within a single filtration to an across filtration representation.Part of this research was conducted when Ozdenoren visited MEDS in Fall 2003. We thank Tapas Kundu, Costis Skiadas, Jean-Marc Tallon and Tan Wang for helpful discussions and also thank audiences at Koc University, Northwestern University, the CERMSEM conference “ Mathematical Models in Decision Theory” at Universite Paris I, and the FUR XI conference on foundations and applications of utility, risk and decision theory     

On the continuity of expected utility

Summary We provide necessary and sufficient conditions for weak (semi)continuity of the expected utility. Such conditions are also given for the weak compactness of the domain of the expected utility. Our results have useful applications in cooperative solution concepts in economies and games with differential information, in noncooperative games with differential information and in principal-agent problems.Work done while visiting the Department of Economics, University of Illinois at Urbana-Champaign.     

Is the expected utility maximization hypothesis refutable by finite market data: The case of two observations

It is shown that with only two observations on the asset demand functions of an investor, it is not possible to refute the hypothesis of expected utility maximization on the part of the investor as long as the axioms of revealed preference are satisfied.     

The reasoning-based expected utility procedure

This paper presents a new iterative procedure for solving finite non-cooperative games, the reasoning-based expected utility procedure (RBEU), and compares this with existing iterative procedures. RBEU deletes more strategies than iterated deletion of strictly dominated strategies, while avoiding the conceptual problems associated with iterated deletion of weakly dominated strategies. It uses a sequence of “accumulation” and “deletion” operations to categorise strategies as permissible and impermissible; strategies may remain uncategorised when the procedure halts. RBEU and related “categorisation procedures” can be interpreted as tracking successive steps in players' own reasoning.     

Strategic games beyond expected utility

This paper argues that Nash equilibrium is a solution where all strategic uncertainty has been resolved and, therefore, inappropriate to model situations that involve ??ambiguity.?? Instead, to capture what players will do in the presence of some strategic uncertainty, takes a solution concept that is closed under best replies. It is shown that such a solution concept, fixed sets under the best reply correspondence, exists for a class of games significantly wider than those games for which generalizations of Nash equilibrium exist. In particular, this solution can do without the expected utility hypothesis.     

Is Kreps-Porteus utility distinguishable from intertemporal expected utility?

Summary In a Lucas (1978) model, with a Kreps-Porteus (1978) nonexpected utility, the following property of equilibrium holds generically in the space of finite-state, Markov output growth rate processes: equilibrium price of equity is distinct from that implied by any intertemporally additive expected utility satisfying specified regularity conditions. In that sense the more general utility functions are observationally distinguishable from the standard expected utility specification.I would like to thank Larry G. Epstein for posing to me the problem studied in this paper and for many suggestions and comments. I am also grateful to Darrell Duffie for helpful suggestions. I am responsible for errors. This papers is part of my Ph.D. thesis at University of Toronto.     

Ambiguous events and maxmin expected utility

We study the properties associated to various definitions of ambiguity [L.G. Epstein, J. Zhang, Subjective probabilities on subjectively unambiguous events, Econometrica 69 (2001) 265-306; P. Ghirardato et al., Differentiating ambiguity and ambiguity attitude, J. Econ. Theory 118 (2004) 133-173; K. Nehring, Capacities and probabilistic beliefs: a precarious coexistence, Math. Soc. Sci. 38 (1999) 197-213; J. Zhang, Subjective, ambiguity, expected utility and Choquet expected utility, Econ. Theory 20 (2002) 159-181] in the context of Maximin Expected Utility (MEU). We show that each definition of unambiguous events produces certain restrictions on the set of priors, and completely characterize each definition in terms of the properties it imposes on the MEU functional. We apply our results to two open problems. First, in the context of MEU, we show the existence of a fundamental incompatibility between the axiom of “Small unambiguous event continuity” (Epstein and Zhang, 2001) and the notions of unambiguous event due to Zhang (2002) and Epstein and Zhang (2001). Second, we show that, in the context of MEU, the classes of unambiguous events according to either Zhang (2002) or Epstein and Zhang (2001) are always λ-systems. Finally, we reconsider the various definitions in light of our findings, and identify some new objects (Z-filters and EZ-filters) corresponding to properties which, while neglected in the current literature, seem relevant to us.     

Subjective expected utility theory with costly actions

This paper explores alternative axiomatizations of subjective expected utility theory for decision makers with direct preferences over actions; including a general subjective expected utility representation with action-dependent utility, and separately additive representations. In the context of the state-space formulation of agency theory, the results of this paper constitute axiomatic foundations of the agent's behavior.     

Upper and lower bounds for expected utility

Summary.   The decision-theoretic literature has developed very few techniques to bound the expected utility of a random variable when only simple statistics like its median or mode or mean are known. One reason for this lack of results is that we are missing a convenient way to link probability theory and expected utility. This paper is written to demonstrate a general (and genuinely probabilistic) technique to obtain upper and lower bounds for the expected utility of a lottery. Received: December 14, 1999; revised version: March 8, 2000     

Background risk in generalized expected utility theory

Summary. In this paper, it is shown that, for a wide range of risk-averse generalized expected utility preferences, independent risks are complementary, contrary to the results for expected utility preferences satisfying conditions such as proper and standard risk aversion. Received: August 10, 2001; revised version: June 18, 2002 RID="*" ID="*"I thank Simon Grant and an anonymous referee for helpful comments and criticism. This research was supported by an Australian Research Council Senior Fellowship and Australian Research Council Large Grant A79800678.     

Testable implications of subjective expected utility theory

I show that the predictive content of the hypothesis of subjective expected utility maximization critically depends on what the analyst knows about the details of the problem a particular decision maker faces. When the analyst does not know anything about the agent's payoffs or beliefs and can only observe the sequence of actions taken by the decision maker any arbitrary sequence of actions can be implemented as the choice of an agent that solves some intertemporal utility maximization problem under uncertainty.     

Testable implications of subjective expected utility theory

I show that the predictive content of the hypothesis of subjective expected utility maximization critically depends on what the analyst knows about the details of the problem a particular decision maker faces. When the analyst does not know anything about the agent's payoffs or beliefs and can only observe the sequence of actions taken by the decision maker any arbitrary sequence of actions can be implemented as the choice of an agent that solves some intertemporal utility maximization problem under uncertainty.     

An expected utility analysis of k-majority rules

Buchanan and Tullok (The calculus of consent: logical foundations of constitutional democracy. University of Michigan Press, Ann Arbor, 1962) argued that the optimal k-majority rule should minimize the sum of external costs and decision costs. Dougherty et al. (Public Choice, 163(1–2):31–52, 2015) formalized their approach using various groups of voters. In this study, we analyze the optimal k-majority rule in terms of expected utility and compare our results to Dougherty et al. (2015), which focuses on costs alone. Specifically, we replace Buchanan and Tullock’s external cost function with an external utility function that accounts for both the benefits and costs of enacting proposals. We find that analyzing k-majority rules in terms of utility, rather than costs, affects the optima. Furthermore, in terms of utility, the optimal k-majority rule can vary depending on the group one expects to be in during a vote. With some interesting exceptions, individuals from groups that favor the proposal often find small k-majority rules optimal. Individuals from groups that oppose the proposal often find large k-majority rules optimal.     

Lexicographic expected utility with a subjective state space

This paper provides a model that allows for a criterion of admissibility based on a subjective state space. For this purpose, we build a non-Archimedean model of preference with subjective states, generalizing Blume et al. (Econometrica 59:61–79, 1991), who present a non-Archimedean model with exogenous states; and Dekel et al. (Econometrica 69:891–934, 2001), who present an Archimedean model with an endogenous state space. We interpret the representation as modeling an agent who has several “hypotheses” about her state space, and who views some as “infinitely less relevant” than others.