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Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

This paper proposes and characterises a model of uncertainty averse preferences that can simultaneously accommodate three divergences from subjective expected utility: imprecision of beliefs (or ambiguity), imprecision of tastes (or multi utility), and state dependence of utility. Moreover, it characterises, in this context, a notion of state independence of utility borrowed from the literature on incomplete preferences. This notion is then shown to be basically inconsistent with the standard state-independence axiom, monotonicity, whenever tastes are imprecise. A new notion of state independence in the context of imprecise tastes, which is characterised by monotonicity, is proposed.

Mots clés : State independence of utility, imprecise tastes, uncertainty aversion, multi utility, multiple priors, state-dependent utility.

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

An ambiguous statistical experiment is a set of joint probability distributions over states and signals. This note compares ambiguous experiments from the point of view of an ambiguity averse decision maker and extends the Blackwell (1951, 1953) ordering to this setting.

Mots clés : experiments, value of information, multiple priors, maximin, rectangularity

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Nudge is a semantically multifarious concept that originates in Thaler and Sunstein's (2008) popular eponymous book. In one of its senses, it is a policy for redirecting an agent's choices by only slightly altering his choice conditions, in another sense, it is concerned with bounded rationality as a means of the policy, and in still another sense, it is concerned with bounded rationality as an obstacle to be removed by the policy, when the latter has a benevolent aim. The paper centres on the interrelations, both semantic and factual, of these three nudge concepts. It argues that the first and second are basically disconnected on Thaler and Sunstein's major examples of nudges, and that this has gone unnoticed to them because they wrongly equate the second with the third concept, and also because they overestimate the explanatory power of behavioural economics, compared with that of classical rational choice theory, to account for successful interventions. After completing this analysis, the paper moves to some of the normative issues raised by Thaler and Sunstein. Their thought-provoking claim that liberalism and paternalism can be reconciled within one and the same doctrine of social ethics - libertarian paternalism – has been subjected to thorough philosophical criticism. Rather than following this abstract line, the paper takes the shortcut of arguing that Thaler and Sunstein lose their best defence of libertarian paternalism after the nudge concepts are disentangled. They had effectively based their case on the view that slight interventions could have powerful effects through a clever use of bounded rationality, and it has been shown that the latter is not really at work in the interventions they consider. The paper finally concludes that the three nudge concepts are worth pursuing, though independently of each other, and in particular that the third one, which involves correcting the pitfalls of bounded rationality, should receive sustained attention from policy analysts

Mots clés : Nudge, liberal paternalism, policy analysis, law and economics, behavioural economics, rational choice theory, Thaler and Sunstein

Départements : Economie et Sciences de la décision, GREGHEC (CNRS), Finance

Using inter-state banking deregulation in the U.S. as an exogenous experiment, we find that a 1% increase in banking integration between U.S. states caused a 0.164-0.184% increase in the foreign exports/domestic shipments ratio for U.S. state level exports in the years 1992-1996. We can ascribe these effects to the integration by banks with foreign assets: a 1% increase in banking integration through such banks caused the exports/domestic shipments ratio to increase by 0.22-0.41% while the expansion of banks with purely domestic assets appears to have no impact. Given our empirical specification, this increase in openness can be attributed to an increase in capital to cover variable and fixed export costs relative to domestic shipping costs and a higher provision of trade finance services. Serving new destinations (the extensive margin defined at the state-country level) accounts for 22% to 28% of the banking integration effect that we observe.

Mots clés : Exports, financial depth, inter-state banking deregulation

Départements : Economie et Sciences de la décision, GREGHEC (CNRS), Finance

We provide the first evidence that changes in risk-based capital requirements for banks affect the real economy through international trade. Using a natural experiment – mandatory Basel II adoption in its Standardized Approach by all banks in Turkey on July 1, 2012 – we investigate the impact of new risk-weights applied to commercial letters of credit (CLC) on that country’s exports to 174 countries. We estimate the resulting payment-term-cost elasticity of CLC-financed trade to be between -0.5 and -1 while the overall trade elasticity to be between -0.032 and -0.179. Calculations suggest that both CLC-related bank pricing and rationing channels are involved.

Mots clés : commercial letters of credit; international trade finance; exports; risk-weights; Basel II

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Judgment (or logical) aggregation theory is logically more powerful than social choice theory and has been put to use to recover some classic results of this field. Whether it could also enrich it with genuinely new results is still controversial. To support a positive answer, we prove a social choice theorem by using the advanced nonbinary form of judgment aggregation theory developed by Dokow and Holzman (2010c). This application involves aggregating classifications (specifically assignments) instead of preferences, and this focus justifies shifting away from the binary framework of standard judgement aggregation theory to a more general one.

Mots clés : Social choice, Judgment aggregation, Logical aggregation, Aggregation of classifications, Assignments, Nonbinary evaluations

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

One apparent reason for deferring a decision – abstaining from choosing, leaving the decision open to be taken by someone else, one’s later self, or nature – is for lack of sufficient confidence in the relevant beliefs. This paper develops an axiomatic theory of decision in situations where a costly deferral option is available that captures this source of deferral. Drawing on it, a preliminary behavioural comparison with other accounts of deferral, such as those based on information asymmetry, is undertaken, and a simple multi-factor model of deferral – involving both confidence and information considerations – is formulated. The model suggests that incorporating confidence can account for cases of deferral that traditional accounts have trouble explaining.

Mots clés : Confidence, multiple priors, deferral, delegation, information acquisition, value of information, incomplete preferences

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

We provide possibility results on the aggregation of beliefs and tastes for Monotone, Bernoullian and Archimedian preferences of Cerreia-Vioglio, Ghirardato, Maccheroni, Marinacci, and Siniscalchi (2011). We propose a new axiom, Unambiguous Pareto Dominance, which requires that if the unambiguous part of individuals’ preferences over a pair of acts agree, then society should follow them. We characterize the resulting social preferences and show that it is enough that individuals share a prior to allow non dictatorial aggregation. A further weakening of this axiom on common-taste acts, where cardinal preferences are identical, is also characterized. It gives rise to a set of relevant priors at the social level that can be any subset of the convex hull of the individuals’ sets of relevant priors. We then apply these general results to the Maxmin Expected Utility model, the Choquet Expected Utility model and the Smooth Ambiguity model. We end with a characterization of the aggregation of ambiguity attitudes.

Mots clés : Preference Aggregation, Social Choice, Uncertainty

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

A theory of incomplete preferences under uncertainty is proposed, according to which a decision maker’s preferences are indeterminate if and only if her confidence in the relevant beliefs does not match up to the stakes involved in the decision. We use the model of confidence in beliefs introduced in Hill (2013), and axiomatise a class of models, differing from each other in the appropriate notion of stakes. Comparative statics analysis can distinguish the decision maker’s confidence from her attitude to choosing in the absence of confidence. The model naturally suggests two possible strategies for completing preferences, and hence for choosing in the presence of incompleteness. One strategy respects confidence – it relies only on beliefs in which the decision maker has sufficient confidence given the stakes – whereas the other goes on hunches – it relies on all beliefs, no matter how little confidence the decision maker has in them. Axiomatic characterizations are given for each of the strategies. Finally, we consider the consequences of the model in markets, where indeterminacy of preference translates into refusal to trade. The incorporation of confidence adds an extra friction, beyond the standard implications of non-expected utility models for Pareto optima

Mots clés : Incomplete preferences, confidence, multiple priors, choice under incomplete preferences, absence of trade

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Simple exchange rate models based on economic fundamentals were shown to have a difficulty in beating the random walk when predicting the exchange rates out of sample in the modern floating era. Using methods from machine learning -- sequential adaptive ridge regression -- that prevent overfitting in-sample for better and more stable forecasting performance out-of-sample we show that fundamentals from the PPP, UIRP and monetary models consistently improve the accuracy of exchange rate forecasts for major currencies over the floating period era 1973-2013 and are able to beat the random walk prediction giving up to 5% improvements in terms of the RMSE at a 1 month forecast. "Classic'' fundamentals hence contain useful information about exchange rates even for short forecasting horizons -- and the Meese and Rogoff (1983) puzzle is overturned. Such conclusions cannot be obtained when rolling or recursive OLS regressions are used as is common in the literature

Mots clés : exchange rates, forecasting, machine learning, purchasing power parity, uncovered interest rate parity, monetary exchange rate models


Département Economie et Sciences de la Décision

Campus HEC Paris
1, rue de la Libération
78351 Jouy-en-Josas cedex


Jeremy GHEZ

Economie - Sciences de la Décision

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