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Mondays 12:15 - 13:15
Location: Ground Floor Library, Department of Economics, Building 081 



25 juin 2012
Pierre Cahuc


11 juin 2012 
Isabelle Méjean (Ecole Polytechnique, Department of Economics)
“Firms, Destinations, and Aggregate Fluctuations”
Joint work with Julian Di Giovanni (IMF and University of Toronto) et Andrei Levchenko (University of Michigan).

Abstract: This paper uses a database covering the universe of French manufacturing firms for the period 1990{2007 to provide a forensic account of the role of individual firms in generating aggregate fluctuations. We set up a simple multi-sector model of heterogeneous firms selling to multiple markets to motivate a theoretically-founded set of estimating equations that decompose firms' annual sales growth rate into different components. We find that the idiosyncratic firm components contribute substantially to aggregate volatility, mattering about as much as the country-level and sectoral components. The finding that idiosyncratic firm-level shocks appreciably a effect aggregate volatility is evidence for the importance of large firms for aggregate fluctuations.


4 juin 2012
François Larmande (EM Lyon) 
"Fishing for excuses and performance evaluation
(joint work with Jean-Pierre Ponssard)

Abstract: The paper studies a principal-agent model in which the agent is sometimes able to provide verifiable evidence that the final result does not accurately reflect his true performance (an excuse). It is assumed that, because of time constraint, generating excuse and exerting productive effort are substitute: a lower productive effort increases the probability of generating verifiable evidence. Necessary and sufficient conditions are obtained for the principal to prefer taking excuses into account instead of using a no-excuse contract. The informativeness of the provision of an excuse plays an important role in the analysis. Whenever the excuse contract is optimal, the agent may or may not be better off , depending on the parameters value. The paper clarifies the issues associated with the well known excuse culture prevailing in some organizations.


Past seminars

14 mai 2012
Bora Erdamar (Institute of Social Sciences, Istanbul Bilgi University, Turkey, Ecole Polytechnique Département d’Economie)

Measuring consensus in a preference-approval context
Joint work with José Luis Garcia-Lapresta, David Pérez-Roman and Remzi Sanver

Abstract : We consider measuring the degree of homogeneity for preference-approval profiles which include the approval information for the alternatives as well as the rankings of them. A distance-based approach is followed to measure the disagreement for any given two preference-approvals. Under the condition that a proper metric is used, we propose a measure of consensus which is robust to some extensions of the ordinal framework. This paper also shows that there exists a limit for increasing the homogeneity level in a group of individuals by simply replicating their preference-approvals.


April 23, 2012
Eduardo Perez 
(Ecole Polytechnique, Department of Economics)
" Certifiable Pre-Play Communication"
Joint work with Alfred Galichon, Jeanne Hagenbach and Frédéric Koessler.

Abstract: Before most important individual decisions and strategic interactions, the concerned parties can communicate with each other and exchange information. When does this communication phase lead to the full revelation of available information? We study this question under the assumption that communication happens through public announcements that are made simultaneously, and that messages are certifiable (agents cannot lie but may reveal partial information). We provide a characterization, and different sets of sufficient conditions that encompass and extend all existence results in the literature. We consider applications to: sender-receiver games, supermodular games, and voting with deliberation.


March 26, 2012
Christian Belzil (Ecole Polytechnique, Department of Economics)
"Dynamic Skill Accumulation, Comparative Advantages, Compulsory Schooling, and Earnings"
Joint work with Jörgen Hansen (Concordia University, CIRANO, CIREQ and IZA) Xingfei Liu (Concordia University)

Abstract: We show that a calibrated dynamic skill accumulation model allowing for comparative advantages, can explain the weak (or negative) effects of schooling on productivity that have been recently reported (i) in the micro literature on compulsory schooling, ii) in the micro literature on estimating the distribution of ex-post returns to schooling, and (iii) in the macro literature on education and growth. The fraction of the population more effcient at producing skills in the market than in school is a pivotal quantity that determines the sign (and magnitude) of different parameters of interest.
Our model reveals an interesting paradox; as low-skill jobs become more skill-enhancing (ceteris paribus), IV estimates of compulsory schooling become increasingly negative, and ex-post returns to schooling (inferred froma Roy model specification of the earnings equation) become negative for an increasing fraction of the population. This arises even if each possible input to skill production has a strictly positive effect. Finally, our model provides a foundation for the weak (or negative) effect education on growth measured in the empirical literature.

March 19, 2012
Vanina Forget (Ecole Polytechnique, Department of Economics)
"Green Signaling in Experimental Private Equity Negotiations"
Joint work with Jim Engle-Warnick 
(McGill U. / CIRANO, Montréal)

Abstract: The market of socially responsible investments, that is investments integrating social, environmental and ethical considerations, has witnessed a striking growth curve over the last decade and is now spreading to the private equity industry. From an agency theory perspective, private equity investors spending resources to provide public good appears paradoxical. This paper asks whether environmental performance could constitute a money-burning signal to reduce information asymmetry in private equity negotiations. Our contribution is to present an experiment with an original signaling investment game that allows comparing green signals (providing real public good) to conventional ones. Main finding is that the existence of a green signal enhances firm type separation and equity market transparency. However, in line with the public good decay literature, green signaling quickly falls. Type separation in presence of the public good provision opportunity further occurs through prices. We suggest the presence of the public good provision crowds-in actors’ intrinsic motivation to act in line with their moral value and to reveal their type. We discuss the positive  effects socially responsible investments might have on equity market transparency and society.



March 12, 2012
Marta Vicarelli (Yale Institute)

"El Nino and Mexican children: medium-term effects of early-life weather shocks on cognitive and health outcomes".
Abstract: El Nino Southern Oscillation (ENSO) is a recurrent climatic event that causes severe weather shocks. This paper employs ENSO-related  foods at the end of the agricultural season to identify medium-term effects of negative conditions in early child development. The analysis shows that, four to five years after the shock, children exposed to it during their early stages of life have test scores in language development, working-memory, and visual-spatial thinking abilities that are 11 to 21 percent lower than same aged children not exposed to the shock. Negative effects are also found on anthropometric characteristics: children affected during their early life stages exhibit lower height (0:42 to 0:71 inches), higher likelihood of stunting (11 to 14 percentage points), and lower weight (0:84 pounds) than same aged children not affected by the shock. Negative effects of weather shocks on income, food consumption, and diet composition during early childhood appear to be key mechanisms behind the impacts on children's outcomes. Finally, no mitigation effects were found from the provision of the Mexican conditional cash transfer program Progresa on poor rural households with children affected by ENSO-related shocks.


March 5, 2012
Tetsuya Kaji (University of Tokyo)
"Structural Estimation of the Japanese Marriage Market as a Finite-horizon Dynamic Matching Model"

 Abstract: Japan faces severe tendency of later marriage and less marriage. A survey shows that search friction could be an important factor behind this tendency. I propose a model that takes into account search friction for both sexes, under the assumption that an agent can only search for a finite and fixed period of time. I assume utility to be divisible and transferable, and employ Nash bargaining as a mechanism of marital decisions. I then propose maximum likelihood estimation of the induced marriage process, and estimate the model using the data of recent Japan's marriage profiles. I find that the estimated coproduction function exhibits supermodularity so that the surplus of a nearly-aged couple is generally larger than that of a May and December couple. I also find that the estimated terminal value of singlehood is sharply decreasing in men's expected wage (at the exit age) while it remains at in women's. Consequently the level and shape of the terminal value differ significantly in each sex at low wages and at the highest wage. It indicates that sustaining men's wage over 2,000 yen per hour is crucial in promoting marriage. The result may also be an indirect evidence of deviation of the reality from the assumptions of transferable utility and/or Nash bargaining.


January 9, 2012

Pierre Picard (Ecole Polytechnique, Department of Economics)

"Fraudulent Claims and Nitpicky Insurers"

Joint work with Jean-Marc Bourgeon (Ecole Polytechnique, Department of Economics and INRA)

Abstract: Insurance fraud is a major source of inefficiency in insurance markets. A self-justification of fraudulent behavior is that insurers are bad payers who start nitpicking if an opportunity arises, even in circumstances where the good-faith of the policy holders is not in dispute. We relate this nitpicking activity to the inability of insurers to commit to an auditing policy. Reducing the indemnity payments acts as an incentive device for the insurer since auditing is profitable even if the claim is not fraudulent. We show that while nitpicking is not optimal when insurers are able to commit to their auditing strategy, it is optimal when they are unable to do so, which explains the prevalence of nitpicking in insurance markets. As optimal cut levels are bounded above, the insurer must sometimes refrain his possibility to reduce the indemnity payment below what is legally possible. We also investigate the reputation problem assuming policyholders incur a morale cost defrauding the insurer that decreases with the intensity of the insurer’s nitpicking activity. We show that despite this induced morale effect, nitpicking remains optimal.


December 12th
Edouard CHALLE 
(Ecole Polytechnique, Department of Economics and Banque de France)
"Equilibrium Risk Shifting and Interest Rate in an Opaque Financial System"
 Joint work with Benoit Mojon (Banque de France) and Xavier Ragot ( Banque de France and PSE).

Abstract:We analyse the risk-taking behaviour of heterogenous intermediaries that are protected by limited liability and choose both their amount of leverage and the risk exposure of their portfolio. Due the opacity of the financial sector, outside providers of funds cannot distinguishing  "prudent" intermediaries from those "imprudent" ones that voluntarily hold high-risk portfolios and expose themselves to the risk of bankrupcy. We show how the number of imprudent intermediaries is determined in equilibrium  jointly with the interest rate, and how both ultimately depend on the cross-sectional distribution of intermediaries' capital. One implication of our analysis is that an exogenous increase in the supply of funds to the intermediary sector (following, e.g., capital inflows) lowers interest rates and raises the number of imprudent intermediaries (the risk-taking channel of low interest rates). Another one is that easy financing may lead an increasing number of intermediaries to gamble for resurection following a bad shock to the sectorís capital, again raising economy wide systemic risk (the gamblingfor-resurection channel of falling equity).


December 5th (12h30)
(Ecole Polytechnique, Department of Economics)
 "The Dynamics of Protection and Imitation of Innovations"
Joint paper with Emeric Henry (Sciences Po)


November 28th
Jörgen WEIBULL (Stockholm School of Economics)
"Evolutionarily stable social preferences under incomplete information"
Joint work with Ingela Alger (Toulouse School of Economics)


November 14th 
(Ecole Polytechnique, Department of Economics)
"Of Roommates and Same-Sex Unions"
Joint work with P-A Chiappori ( Department of Economics School of Arts and Sciences Columbia University) Bernard Salanié (Columbia Université - Ecole Polytechnique)


November 7th 
As previously announced, our 2nd PhD Day will take place on Monday, November 7 (9am-5:30pm)


October 24th
(Ecole Polytechnique, Department of Economics)
"The development of SRI in France: an economic analysis of the role of quality-signalling schemes"


October 17th
(Ecole Polytechnique Département d'Economie)
Incentives to Work or Incentives to Quit? "


October 10th 
Marcel BOYER

(Université de Montréal, Ecole Polytechnique, CIRANO)
"The Determination of Optimal Fines in Cartel Cases The Myth of Underdeterrence
Joint work with Marie-Laure Allain (École Polytechnique) Rachidi Kotchoni (Université Laval ) Jean-Pierre Ponssard (École Polytechnique)