Ambiguity Aversion and Cost-Plus Procurement Contracts

This paper presents a positive theory about the contractual form of procurement contracts under cost uncertainty. While the cost of manufacture is uncertain it can be controlled, to an extent depending on the effort exerted by the agent. The effort exerted by the agent is not contractible but causes disutility to the agent. Hence, the amount of effort exerted depends on the power of incentives built into the terms of reimbursement agreed to in the contract. The analysis in the paper explicitly models the possibility that the belief about the cost uncertainty is ambiguous, in the sense that belief is described by a set of probabilities, rather than by a single probability. This allows us to incorporate ambiguity aversion (behavior of the kind seen in Ellsberg`s "paradox") into the players` objective functions. The paper finds that, provided the agent is more averse to ambiguity than the principal, the more the ambiguity of belief the lower the power of the optimal incentive scheme. The fix-price contract is optimal if there is no ambiguity, but if the ambiguity is high enough a cost-plus contract is optimal; in between, a cost-share scheme is optimal. It is contended that the finding is particularly useful in explaining facts about the wide use of cost-plus and similar low powered contracts in research and development (R&D) procurement by the U.S. Department of Defense.Procurement contracts, Incentive contracts, Uncertainty aversion, Ellsberg`s paradox, Cost reimbursement contracts, Cost-plus contracts, Fixed price contracts

An overview of economic applications of David Schmeidler`s models of decision making under uncertainty

This paper surveys some economic applications of the decision theoretic framework pioneered by David Schmeidler to model effects of ambiguity. We have organized the discussion principally around three themes: financial markets, contractual arrangements and game theory. The first section discusses papers that have contributed to a better understanding of financial market outcomes based on ambiguity aversion. The second section focusses on contractual arrangements and is divided into two sub-sections. The first sub-section reports research on optimal risk sharing arrangements, while in the second sub-section, discusses research on incentive contracts. The third section concentrates on strategic interaction and reviews several papers that have extended different game theoretic solution concepts to settings with ambiguity averse players. A final section deals with several contributions which while not dealing with ambiguity per se, are linked at a formal level, in terms of the pure mathematical structures involved, with Schmeidler`s models of decision making under ambiguity. These contributions involve issues such as, inequality measurement, intertemporal decision making and multi-attribute choice.Ellsberg Paradox, Ambiguity aversion, Uncertainty aversion

Ambiguity aversion and the absence of wage indexation

This paper analyzes optimal wage contracting assuming agents are not subjective expectedutility maximizers but are, instead, ambiguity (or uncertainty) averse decision makers whomaximize Choquet expected utility. We show that such agents will choose not to include anyindexation coverage in their wage contracts even when inflation is uncertain, unless theperceived inflation uncertainty is high enough. Significantly, the exercise does not presume anyexogenous costs (e.g., transactions costs) of including indexation linksambiguity aversion; indexation

Ambiguity Aversion and Incompleteness of Financial Markets

It is widely thought that incomes risks can be shared by trading infinancial assets. But financial assets typically carry some riskidiosyncratic to them, hence, disposing incomes risk using financial assetswill involve buying into the inherent idiosyncratic risk. However, standardtheory argues that diversification would reduce the inconvenience ofidiosyncratic risk to arbitrarily low levels. This argument is less robustthan what standard theory leads us to believe: ambiguity aversion canexacerbate the tension between the two kinds of risks to the point thatclasses of agents may not want to trade some financial assets. Thus,theoretically, the effect of ambiguity aversion on financial markets is tomake the risk sharing opportunities offered by financial markets lesscomplete than it would be otherwise.incomplete markets; ambiguity aversion

Recursive Smooth Ambiguity Preferences

This paper axiomatizes an intertemporal version of the Smooth Ambiguity decision model developed in Klibanoff, Marinacci, and Mukerji (2005). A key feature of the model is that it achieves a separation between ambiguity, identified as a characteristic of the decision maker's subjective beliefs, and ambiguity attitude, a characteristic of the decision maker's tastes. In applications one may thus specify/vary these two characteristics independent of each other, thereby facilitating richer comparative statics and modeling flexibility than possible under other models which accomodate ambiguity sensitive preferences. Another key feature is that the preferences are dynamically consistent and have a recursive representation. Therefore techniques of dynamic programming can be applied when using this model.Ambiguity, Uncertainty, Knightian Uncertainty, Ambiguity Aversion, Uncertainty Aversion, Ellsberg Paradox, Dynamic Decision Making, Dynamic Programming under Ambiguity, Smooth Ambiguity.

A smooth model of decision making under ambiguity.

We propose and axiomatize a new model of preferences that achieves a separation between ambiguity, identified as a characteristic of the decision maker's subjective information, and ambiguity attitude, a characteristic of the decision maker's tastes.Ambiguity; Uncertainty; Knightian Uncertainty; Ambiguity Aversion; Uncertainty Aversion; Ellsberg Paradox

Comment on Ellsberg's two-color experiment, portfolio inertia and ambiguity

The final step in the proof of Proposition 1 (p.311) of Mukerji and Tallon (2003) may not hold in generalbecause $\varepsilon>0$ in the proof cannot be chosen independently of $w,z$. We point out by a counterexample that the axioms they impose are too weak for Proposition 1. We introduce a modified set of axioms and re-establish the propositionambiguity;bid ask spread;Ellsberg paradox

The strength of sensitivity to ambiguity

We report an experiment where each subject’s ambiguity sensitivity is measured by an ambiguity premium, a concept analogous to and comparable with a risk premium. In our design, some tasks feature known objective risks and others uncertainty about which subjects have imperfect, heterogeneous, information (“ambiguous tasks”). We show how the smooth ambiguity model can be used to calculate ambiguity premia. A distinctive feature of our approach is estimation of each subject’s subjective beliefs about the uncertainty in ambiguous tasks. We find considerable heterogeneity among subjects in beliefs and ambiguity premia; and that, on average, ambiguity sensitivity is about as strong as risk sensitivity

Discriminating between models of ambiguity attitude: a qualitative test

During recent decades, many new models have emerged in pure and applied economic theory according to which agents’ choices may be sensitive to ambiguity in the uncertainty that faces them. The exchange between Epstein (2010) and Klibanoff et al. (2012) identified a notable behavioral issue that distinguishes sharply between two classes of models of ambiguity sensitivity that are importantly different. The two classes are exemplified by th