Working papers results

The problemof choosing an optimal toolkit day after day,when there is uncertainty concerning the value of different tools that can only be resolved by carrying the tools, is a multi-armed bandit problem with nonindependent arms. Accordingly, except for very simple specifications, this optimization problem cannot (practically) be solved. Decision takers facing this problem presumably resort to decision heuristics, "sensible" rules fordeciding which tools to carry, based on past experience. In this paper, we examine and compare the performance of a variety of heuristics, some very simple and others inspired by the computer-science literature on these problems. Some asymptotic results are obtained, especially concerning the long-run outcomes of using the heuristics, hence these results indicate which heuristics do well when the discount factor is close to one. But our focus is on the relative performance of these heuristics for discount factors bounded away from one, which we study through simulation of the heur istics on a collection of test problems.

Recent applications to the modeling of emission permit markets by means of stochastic dynamic general equilibrium models look into the relative merits of different policy mechanisms under uncertainty. The approach taken in these studies is to assume the existence of an emission constraints that is always binding (i.e. the emission cap is always smaller than what actual emissions would be in the absence of climate policy). Although this might seem a reasonable assumption in the longer term, as policies will be increasingly stringent, in the short run there might be instances where this assumption is in sharp contrast with reality. A notable example would be the current status of the European Emission Trading Scheme. This paper explores the implications of adopting a technique that allows occasionally, rather than strictly, binding constraints. With this new setup the paper sets out to investigate the relative merits of different climate policy instruments under different macro-economic shocks.

Previous research has documented a behavioral distinction between 'social risk' and financial risk. For example, individuals tend to demand a premium on the objective probability of a favorable outcome when that outcome is determined by a human being instead of a randomizing device (Bohnet, Greig, Herrmann, and Zeckhauser 2008; Bohnet and Zeckhauser 2004). In this paper we ask whether social risk is always aversive, answering in the negative and identifying factors that can eliminate, or even change the sign of, the social risk premium. Motivated by the stereotype content model from the social psychology literature, which we argue has straightforward predictions for situations involving social risk (Fiske, Cuddy, and Glick 2007), we focus on two factors: 'warmth', synonymous with intent, and 'competence.' We investigate these factors using a between-subjects experimental design that implements slight modifications of the binary trust game of Bohnet and Zeckhauser across treatments. Our results indicate that h aving risk generated by another human being does not, on its own, lead to a social risk premium. Instead, we find that a positive risk premium is demanded when a counter-party has interests conflicting with one's own (low warmth) and, additionally, is competent. We find a negative social risk premium -i.e., social risk seeking- when the counter-party has contrary interests but lacks competence.

Reciprocity can be a powerful motivation for human behaviour. Scholars argue that it is relevant in the context of private provision of public goods. We examine whether reciprocity can resolve the associated coordination problem. The interaction of reciprocity with cost-sharing is critical. Neither cost-sharing nor reciprocity in isolation can solve the problem, but together they have that potential. We introduce new network notions of reciprocity relations to better understand this. Our analysis uncovers an intricate web of nuances that demonstrate the attainable yet elusive nature of a unique outcome.

Maccheroni, Marinacci, and Rustichini [17], in an Anscombe-Aumann framework, axiomatically characterize preferences that are represented by the variational utility functional where u is a utility function on outcomes and c is an index of uncertainty aversion. In this paper, for a given variational preference, we study the class of functions c that represent V. Inter alia, we show that this set is fully characterized by a minimal and a maximal element, c* and d*. The function c*, also identified by Maccheroni, Marinacci, and Rustichini [17], fully characterizes the decision maker's attitude toward uncertainty, while the novel function d* characterizes the uncertainty perceived by the decision maker.

Land conflicts in developing countries are costly. An important policy goal is to create respect for borders. This often involves mandatory, expensive interventions. We propose a new policy design, which in theory promotes neighborly relations at low cost. A salient feature is the option to by-pass regulation through consensus. The key idea combines the insight that social preferences transform social dilemmas into coordination problems with the logic of forward induction. As a first, low-cost pass at empirical evaluation, we conduct an experiment among farmers in the Ethiopian highlands, a region exhibiting features typical of countries where borders are often disputed. Our results suggest that a low-cost land delimitation based on neighborly recognition of borders could deliver a desired low-conflict situation if accompanied by an optional higher cost demarcation process.

The hot hand fallacy has long been considered a massive and widespread cognitive illusion with important economic consequences. While the canonical domain of the fallacy is basketball, which continues to provide its strongest and most readily generalizable supporting evidence, the fallacy has been considered as a candidate explanation for various economic and financial anomalies. We find, in its canonical domain, that the belief in the hot hand is not a fallacy, and that, surprisingly, the original evidence supports this conclusion. Our approach is to design a controlled shooting field experiment and develop statistical measures that together have superior identifying power over previous studies. We find substantial evidence of the hot hand, both in our study and in all extant controlled shooting studies, including the seminal study (which found the opposite result, and coined the term ''the hot hand fallacy''). Also, we observe the hot hand effect to be heterogeneous across shooters, which suggests that decision makers (e.g. players and coaches) may have incentive to identify which shooters have a greater tendency to become hot. Accordingly, we find evidence that expert players (teammates) can do so. In light of these results, we reconsider the economic relevance of the hot hand fallacy more generally.

Does democracy make politicians accountable? The UK expenses scandal of May 2009 constitutes an ideal setting to answer this question, since it allows credible ceteris paribus comparisons. We show that scandal-related press coverage significantly increased the probability of an MP to retire, reduced vote shares of standing MPs, but did not decrease their re-election probability. We also show that punishment was directed to individual MPs involved in the scandal rather than their parties. An objective monetary measure of malfeasance from an official report explains press coverage but has no independent effect on MPs' retirement or vote shares. We show that voters perceive co-partisan MPs to be less involved than other MPs. Finally we analyse coverage of the scandal by seven national newspapers and conclude that the press worked as a watchdog by focussing on the government and on frontbenchers of the main opposition party, with little role for ideological leanings. Our study also uncovers a substantial gender bias: ceteris paribus, female MPs received more media attention and, for the same level of media attention, were more likely to stand down.

A decision maker can experiment on up to two alternatives simultaneously over time. One and only one of these alternatives can produce successes, according to a Poisson process with known arrival rate; but there is uncertainty as to which alternative is the profitable one. The decision maker only observes the outcomes of the alternatives chosen, and choosing each alternative entails a cost. Simultaneous experimentation involves higher costs but can produce more data. At the same time, since the alternatives are negatively correlated, the outcomes of either one are informative about the other. If the costs are high and she is sufficiently impatient, the decision maker never experiments on both alternatives at once. Otherwise, if she starts with a single alternative that produces no successes, she becomes gradually pessimistic and eventually takes on the other alternative while keeping the first one - despite the higher costs and the negative correlation.

A model of 'harassment bribes,' paid for services one is entitled to, is developed to analyze
the proposal to legalize paying these bribes while increasing fines on accepting them.
We explore performance as regards corruption deterrence and public service provision. Costs of verifying reports make the scheme more effective against larger bribes and where institutions' quality is higher. A modified scheme, where immunity is conditional on reporting, addresses some key objections. The mechanism works better against more distortionary forms of corruption than harassment bribes, provided monetary rewards can compensate bribers for losing the object of the corrupt exchange. Results highlight strong complementarities with policies aimed at improving independence and accountability of law enforcers.