Yusuke Osaki

Production and Hedging Decisions under Smooth Ambiguity Aversion

This paper considers production and hedging decisions of firms under ambiguous price risk. We display that the separation property and the full hedging theorem hold in the presence of ambiguity. We also determine the condition that ambiguity aversion increases optimal hedging position.

HEDGING AND THE COMPETITIVE FIRM UNDER AMBIGUOUS PRICE AND BACKGROUND RISK

This paper examines the optimal production and hedging decisions of the competitive firm that possesses smooth ambiguity preferences and faces ambiguous price and background risk. The separation theorem holds in that the firms optimal output level depends neither on the firms attitude towards ambiguity nor on the incident to the underlying ambiguity. We derive necessary and sufficient conditions under which the full-hedging theorem holds and thus options are not used. When these conditions are violated, we show that the firm optimally uses options for hedging purposes if ambiguity is introduced to the price and background risk by means of mean-preserving spreads. We as such show that options play a role as a hedging instrument over and above that of futures.

Regret-sensitive treatment decisions

The threshold approach to medical decision-making, in which treatment decisions are made based on whether the probability of sickness exceeds a predetermined threshold, was introduced by (Pauker and Kassirer, N Engl J Med 293:229-234, 1975) and (Pauker and Kassirer, N Engl J Med 302:1109-1116, 1980). This study generalizes the threshold approach using regret theory. Regret theory is one of the established alternatives to expected utility theory (EUT), and partly overcomes the descriptive limitations of EUT. Under regret theory, agents suffer disutility from regret or enjoy utility from rejoicing by comparing the chosen alternative with the forgone one. We examine the effect of regret and rejoicing on the threshold approach by setting the EU case as a benchmark, and show conditions under which regret and rejoicing monotonically change the threshold probability. The threshold probability is lowered by regret and rejoicing under the reasonable condition in the sense that the condition can explain observed choices that EU fails to describe. This suggests that agents opt to undergo medical treatment by the feeling of regret and rejoicing. This result might explain the social problems that occur in relation to the public provision of medical services in many OECD countries such as medical expenditure rising faster than government forecasts. The results also imply that regret sensitivity might cause inequality of benefits from public medical services. Finally, we offer a solution to this problem.

Optimal Penalty and Accounting Policy

ABSTRACT This study considers risky investment projects under adverse selection and examines optimal penalties for erroneous auditing reports to maximize social welfare. These penalties give firms an incentive to choose accounting policies that maximize social welfare. We characterize the optimal penalties such that efficient firms choose an aggressive accounting policy and inefficient firms choose a conservative accounting policy.

A Local Index of Risk Apportionment

Eeckhoudt and Schlesinger (2006) introduced a particular class of lottery pairs to characterize the direction of higher-order risk preferences. Using their framework, this paper proposes a new index of higher-order risk aversion to measure the intensity of higher-order risk preferences. Borrowing their terminology, it is called a local index of risk apportionment. Paying attention to the structure of the lottery pairs, we develop a systematic way of characterizing the index of risk apportionment.