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• December 21th 2023 : Yannick Guyonvarch (PSAE) - “Inference with multi-indexed data: a review of recent advances and remaining challenges”, joint with Xavier D'Haultfoeuille et Laurent Davezies

Empirical  researchers routinely have to deal with multi-indexed data. For instance, trade flows may be indexed by time, importer, exporter and type of good. These data naturally exhibit network-type dependence or multiway clustering along the different indices. Handling such dependence structures can prove challenging. In particular, it is often not obvious a priori whether clustering/dependence should be accounted for along only some dimensions or all at the same time. In the trade example, this boils down to the well-known practical question: "Should I cluster at the importer, exporter or importer-and-exporter level?". These issues get even more complex when fixed effects get included in the picture. In this talk, I will present a series of recent research articles I have been working on that seek to give both a better theoretical understanding and simple practical guidelines to researchers working with multi-indexed data.

• December 12th 2023 : José De Sousa (Paris 2 Assas) - “Delivering Us from Crime? Online Platforms, Gig Jobs, and Offending”, joint with Hugo Allouard, Grazia Cecere, Olivier Marie and Inès Picard

We investigate the impact of food-delivery platforms on local economies and crime rates in France. Using the temporal and geographic variation in the deployment of these platforms across cities, our research adopts a staggered difference-in-differences approach to analyze how the gig economy reshapes urban socio-economic dynamics. Preliminary results indicate that the entry of these platforms in employment zones correlates with an increase in the number of registered deliverers and a reduction in drug-related cases, with no significant impact on theft-related crimes.

• December 5th 2023 : Laurent Gobillon (PSE, CNRS) - “Urbanization and urban divergence: France c. 1760-2020” avec Pierre-Philippe Combes, Gilles Duranton, Clément Gorin et Frédéric Robert-Nicoud

We use a combination of image processing and machine learning tools to extract data from historical maps of France. Granular information about the distribution of population allows us to delineate cities consistently (and relatively) over 260 years. Against a backdrop of rising population, the rate of urbanization increased but the number of cities declined and the size distribution of cities also became increasingly skewed. Within cities, population density rose and its gradient flattened. To bring these facts together, we propose a model of urban divergence for which we verify further empirical predictions.

• November 30th 2023 : Juan-Pablo Montero (PUC-Chile) - “Pricing Congestion to Increase Traffic: The Case of Bogota” with Felipe Sepulveda and Leonardo Basso

In September 2020, the city of Bogota introduced a major market-based reform to its odd-even driving restriction, better known as Pico y Placa. Drivers now have the option to pay a daily fee to be exempted from the restriction. Despite the increase in traffic—a 9% drop in average speed—we find substantial welfare gains from the reform, US$222 million per year. An important fraction of these gains—31%—comes from simply “abolishing” the restriction, i.e., setting the exemption fee equal to zero; the rest from setting a strictly positive fee, US$9 per day. The big winners of the reform are middle-income individuals who now use their cars more often, whereas the big losers are high-income individuals who now spend more time in traffic (their annual gains and losses amount to US$759 million and US$506 million, respectively).

• November 28th 2023 : Raouf Boucekkine (AMSE) - “Spatiotemporal dynamics : optimal control and games with applications to transboundary pollution”

We use a combination of image processing and machine learning tools to extract data from historical maps of France. Granular information about the distribution of population allows us to delineate cities consistently (and relatively) over 260 years. Against a backdrop of rising population, the rate of urbanization increased but the number of cities declined and the size distribution of cities also became increasingly skewed. Within cities, population density rose and its gradient flattened. To bring these facts together, we propose a model of urban divergence for which we verify further empirical predictions.

• November, 23th 2023 : Liang Diao (Inrae-Cesaer) - “Does Improved Tenure Security Reduce Fires? Evidence from the Greece Land Registry” avec Huiqian Song

While tenure security is essential to effective land management, there is little empirical evidence on its environmental impact. We show that improving tenure security reduces fires. Exploiting the staggered rollout of the Hellenic Cadastre program across Greece, we find those regions covered by the mandatory land registry witnessed large declines in agricultural fire events, burned areas, and air pollutants. Agricultural data reveal the mechanism: the improved tenure security under the program leads to farming expansion and larger investments; to protect the land-attached investments, the landowners mitigate fire risks through stocking more fire-suppression equipment and practicing more long-term oriented land management.

• November 16th 2023 : Mathieu Parenti (PSE, INRAE) - “Profit Shifting Frictions and the Geography of Multinational Activity”

International tax rules are commonly viewed as obsolete as multinational corporations exploit loopholes to move their profits to tax havens. This paper uncovers how international tax reforms can curb profit shifting and impact real income and welfare across nations. We build a model of international corporate tax avoidance under imperfect competition that disentangles profits that stem from real economic activity from paper profits that are booked in tax havens. Our framework delivers a set of « triangle identities » through which we recover bilateral profit-shifting flows. Using different data sources ranging from publicly available to firm-level datasets, we find an elasticity of paper profits that is three times larger than the elasticity of the tax base. In our quantitative model, a global minimum tax increases welfare by inducing higher tax revenues and public good provision. It also encourages countries to raise their statutory corporate tax rates as it effectively reduces tax competition. Instead, a border adjustment tax (BAT) that eliminates profit shifting distorts multinational production and may result in welfare losses. A tax reform in the spirit of the destination-based cash-flow tax, combining a BAT with a reduction in the corporate income tax rate may induce efficiency gains at the expense of public good provision.

• November 14th 2023 : Rémi Generoso (Université de Lille) - “The financial cost of stabilizing US farm income under climate change”, co -écrit avec Cécile Couharde (Université Paris Nanterre)

The paper assesses the financial cost of federal farm programs in mitigating income losses due to drier conditions expected from climate change. Our study encompasses agricultural-producing counties within the conterminous United States during the census years from 2002 to 2017. We quantify historical drought patterns and their projected trends for the near (2020-2049) and more distant (2030-2059) future, using climate reanalysis data and 20 downscaled global circulation model products from the Coupled Model Intercomparison Project 5. We estimate the relationship between federal agricultural payments and climate change by analyzing how farm income losses due to drier conditions affect the magnitude and distribution of these payments under the RCP 8.5 scenario. We predict that, under unmitigated climate change, payments from federal farm program should significantly increase to maintain their income-stabilization capacity, with a greater likelihood of much larger financial costs when accounting for statistical and climate uncertainties.

• November, 9th 2023 : Derya Keles (INRAe - Beta) - “Weather shocks and pesticide purchases” , with François Bareille and Raja Chakir

This paper investigates whether farmers adapt their pesticide use to cope with climate change. Using a unique, exhaustive dataset detailing pesticide purchases per zip code in France between 2014 and 2019, we econometrically explain pesticide purchases by weather during the growing season. We identify heterogeneous weather impacts across types of pesticides, seasons and locations. Our preferred estimates using average temperature indicate that a +1% temperature increase during the growing season leads to use additional +1.66% pesticides. Because our analyses suggest limited year-to-year pesticide storage and farmers' adaptation along other margins, we interpret these estimates as causal weather impacts on pesticide use.

• November, 7th 2023 : Stefan Ambec (TSE - INRAe) - “The economics of carbon leakage mitigation policies”

In a trade model with endogenous emissions abatement, we investigate the im- pact of three policy instruments aimed at mitigating carbon leakage: free emission allowances, Carbon Border Adjustment Mechanism (CBAM) and CBAM with export rebates. We show that providing allowances for free does not alter the incentives to abate carbon emissions, but fosters the entry of more carbon intensive producers. It levels the “playing field” both domestically and internationally, and it may even re- verse the carbon leakage. In contrast, the CBAM levels the playing field only domes- tically, and it may lead to an autarky equilibrium. To reverse the carbon leakage, the CBAM must be complemented with export rebates. We further show that the CBAM increases welfare for any share of free allowances, and identify the optimal share of free allowances with or without CBAM. Finally, we perform a calibration exercise on cement and steel sectors to simulate the effects of the CBAM recently adopted by the European Union. Our model predicts a scenario with reverse carbon leakage and significant welfare gains for both sectors.

• June 27th, 2023 :Jeanne Hagenbach (Sciences Po Paris) - “Motivated Skepticism”, joint with Charlotte Saucet (University of Paris 1)

We experimentally study how individuals read strategically-transmitted information when they have preferences over what they will learn. Subjects play disclosure games in which Receivers should interpret messages skeptically. We vary whether the state that Senders communicate about is ego-relevant or neutral for Receivers, and whether skeptical beliefs are aligned or not with what Receivers prefer believing. Compared to neutral settings, skepticism is significantly lower when it is self-threatening, and not enhanced when it is self-serving. These results shed light on a new channel that individuals can use to protect their beliefs in communication situations: they exercise skepticism in a motivated way, that is, in a way that depends on the desirability of the conclusions that skeptical inferences lead to.

• June 20th, 2023 : Koos Gardebroek - “Developments and Challenges in Dutch Agriculture: The Nitrogen Problem and Related Issues"

Like in many European countries, The Netherlands also has to reduce its nitrogen surpluses. In May 2019 the highest Dutch court judged that the existing Dutch emission policies violated Dutch law and EU policies, in particular The Habitats Directive. This led to a substantial policy crisis and ongoing farmers’ protests. This seminar discusses the background of the nitrogen problem in the Netherlands and the complexity of proposing robust policies out of this situation.

• June, 13th 2023 - Ondine Berland (PSAE) - “Households’ Food Carbon Footprint​”

Around a quarter of global greenhouse gas emissions comes from food systems. Designing policies to reduce food-related emissions requires an adequate representation of the heterogeneity of households’ food demand response to economic shocks (prices, disposable income) and how this response affects food-related emissions. I use detailed household purchase-level data from France to (i) build a unique database systematically bridging food purchases and environmental information, (ii) document differences across food products and households in emissions, (iii) study a counterfactual scenario in which households’ food budget is reduced and evaluate the associated impacts on food carbon footprints. Preliminary results suggest that low-emitting households differ substantially from high-emitting ones, both in terms of socio-characteristics and reactions.

• June, 6th 2023 - Thais Nunez Rocha (LEO- Université d'Orléans) - “What type of trade is promoted by environmental regulations?"

The objective of this paper is to investigate the extent to which international trade is affected by environmental stringency. The impact of environmental regulations on exports is evaluated by using a gravity model of trade, which is estimated for a global sample of countries over the period from 1995 to 2015, distinguishing between clean, footloose, and dirty products. This enables us to investigate whether more stringent environmental provisions and environmental laws lead countries to relocate dirty production and exports, as predicted by the Pollution Haven Hypothesis. Data on environmental provisions that are legally enforceable is obtained from the Deep Trade Agreement dataset (World Bank) and environmental laws and treaties are from Ecolex. Our results show that, in aggregated form for the deeper environmental provision we can expect a decrease in trade of “normal” goods, but not those of the dirty and footloose products. When focusing about the combinations with legislation, only national laws seem being working. The environmental provisions and laws, de jure, the domestic legislation does exert a significant effect on trade, we observe a decrease in trade of the deepest categories of the provisions but this only holds for footloose and not dirty products and is mostly true for the exporter, and combined with the deepest environmental provisions, confirming the Pollution Haven Effect.

• May 30th, 2023 : Etienne Lorang (Tilburg University) - "When Pigouvian waste taxes (cannot) implement the first-best in general equilibrium"

We introduce a framework for the representation of material flows in a competitive equilibrium. Material balances track material flows, and adjust endogenously to economic transactions. The simple theoretical model shows that taxing waste where generated does not restore the optimum while taxing resource extraction does. We show that Hedonic pricing of material content for goods restores the capacity of waste taxes to implement the first-best. The framework can be used in a computable general equilibrium model that adds industrial ecology elements: material balances that fully track material flows and stocks.

• May 23th, 2023 : Arne Uhlendorff (CREST-CNRS) - “Consumption choices and earnings expectations: empirical evidence and structural estimation”

In this paper, we document that households' consumption expenditures crucially depend on their expected earnings - even after controlling for realized earnings, wealth and time-invariant unobserved characteristics such as permanent income and over-confidence. To explain this evidence, we develop and structurally estimate a standard-incomplete markets model in which rational households receive private signals on their future earnings. We find that households' earnings uncertainty is significantly lower than what is typically assumed in incomplete markets models. Facing lower earnings uncertainty, households prefer less progressive earnings taxes.

• May 16th, 2023 : Mathias Reynaert (TSE) - “Colluding Against Environmental Regulation”

We study collusion among firms against imperfectly monitored environmental regulation. Firms increase variable profits by violating regulation and reduce expected noncompliance penalties by violating jointly. We consider a case of three German automakers colluding to reduce the effectiveness of emission control technology. By estimating a structural model of the European automobile industry from 2007 to 2018, we find that the collusion lowers expected noncompliance penalties substantially and increases buyer and producer surplus. Welfare decreases by €0.73–2.51 billion because of increased pollution. We show how environmental policy design and antitrust play complementary roles in preventing noncompliance.

• May 11th, 2023 : Clément Nedoncelle (PSAE) - “Foreign Demand, Soy Exports, and Deforestation”

In this project, we evaluate the credibility of demand-side policies to curb deforestation patterns. Demand-side policies are considered important drivers of deforestation and soy demand. The academic literature remains mostly silent regarding its potential impacts. We focus on the universe of trade in soy, originating from Amazonia, using disaggregated export and production data at the municipality - exporter - destination and year level (TRASE). We estimate whether changes in foreign demand are related to soy exports and soy-related deforestation. Then, we evaluate the role played by soy exporters’ networks and market structure in shaping this elasticity. Finally, we focus on potential aggregation bias when estimating this elasticity.

• April 20th, 2023 : Félix Pasquier (CREST-ENSAE) - “Efficient Elderly Home Care Subsidies”

This early stage project aims at understanding the economic and social mechanisms behind the consumption of non-medicalised elderly home care. The goal consists in evaluating the evolution of the consumption of non-medicalised professional care and informal care provided by the family following a change in the price of formal care. The modeling of the supply of home care is an innovative aspect of the project. The sources of variation exploited for the identification of the model will be the non-linearity of the Allocation Personnalisée d'Autonomie, the main subsidy for professional elderly home care, and the diversity of local market regulations. The data that will be used to estimate the model come from the CARE-ménages survey, a representative sample of the French population over 60 years old.

• April 13th, 2023 : Ninon Moreau-Kastler (ENS Paris-Saclay) - “Due Diligence and Legal Havens: Conflict Minerals Exports in Africa’s Great Lake Region”

This paper studies how « conflict mineral » trade flows react due diligence policies imposing sourcing guidelines for importers, in the presence of legal opacity. Legal opacity is a set of legal loopholes enabling morally reprehensible products to reach global markets. It is supplied by legal havens, jurisdictions endowed with a legal technology ensuring loss of information on economic transactions. I explore this mechanism in the case of conflict mineral trade. I study how Dodd-Frank Act Conflict Mineral Rule imposed new trade costs on minerals by imposing sourcing disclosure and name and shame for U.S. importers. It targets specific "3T" (tin, tantalum and tunsgten) minerals extracted in D.R.C. and adjoining countries. Comparing targeted bilateral trade flows to non-targeted products exporters within the structural gravity framework, I find that this policy decreased targeted countries exports value of 3T products by 70%. However, disclosure is evaded through legal opacity: in a counterfactual exercise, I estimate that 38% of exports to regular trade partners are exported to legal havens after the law is implemented.

• April 11th, 2023 : Olivier Damette (Université de Lorraine - BETA) - “Climate and sovereign risk: the Latin American experience with ENSO events”

Using monthly panel data over the 2007-2019 period for seven Latin American countries, we empirically test the impact of climate oscillations – here ENSO (El Niño Southern Oscillations) on sovereign risk. Local Projections are computed to assess the dynamic response of sovereign spreads to ENSO events. Results show that strong El Nino and La Nina shocks lead to a significant increase in sovereign spreads, but with a different timing. Strong El Nino shock are associated with a significant short-term increase in sovereign spreads, while strong La Nina events are associated with a delayed but significant increase in sovereign spreads after a short-term decrease. Thus, our results suggest a potential asymmetry in the effect of these ENSO events on sovereign risk. We also highlight a high volatility in the dynamics of sovereign spreads, which may reflect an overreaction of investors in the face of the high degree of uncertainty generated by the economic and financial consequences associated with ENSO events. Complementary time-series estimates suggest that Costa Rica and Peru are especially representative of those effects. Overall, our results warn about the fact that, in the case of Latin American countries, weather shocks associated with strong ENSO events have adverse macroeconomic and financial consequences that can lead to an increase in sovereign risk.

• April 4th, 2023 : Markus Nabernegg (Siegen University) - “Environmental Engel Curves with predicted consumption for high-income households: An application for Ecuador”

Studies on the macro level about the relationship between income inequality and carbon emissions champion the idea of a "social dilemma", where inequality reductions lead to emission increases (Kopp and Nabernegg, 2022, Grünewald et al, 2017). A great part of this dilemma is explained on the micro level by the concave relationship between household income and household consumption (and therefore with the emissions embodied in consumption). Nevertheless, empirical evidence for this concave relationship is drawn either directly from household surveys (bottom-up approach) which suffer from undercoverage and underreporting of high-income households (Levinson and O'Brian, 2019, Sager, 2019), or from studies correcting for the income of rich households and then deriving emissions from income through a constant elasticity (top-down approach), whereby the elasticity stems from the same household surveys (Chancel, 2022). Our study assesses the validity of the concave income-emissions relationship for the case of Ecuador, where we have access to exhaustive micro data. The method includes three steps: First, we correct the income distribution of the income and expenditure household survey from 2012 with tax microdata and the application of Distributional National Accounts methods (Blanchet et al, 2020); second, we predict consumption for the corrected high-income households; and third, we associate carbon emissions to the consumption of households through input-output tables. The derived Environmental Engel Curves (EEC) for the bottom-up and top-down approach are compared to the EEC from our methodology. Preliminary results show that our corrections challenge the concavity of the income-emission relationships.

• March 30th, 2023 : Martin Jégard (Swedish University of Agricultural Sciences) - “An Optimal Distribution of Polluting Activities Across Space”

Should air quality policies target industries within the largest cities? On the one hand, we should seek to reduce atmospheric pollutants’ emissions in places where most of the population is concentrated. On the other hand, more stringent policies can hurt local industries and targeting the cities that contribute the most economically may decrease welfare. Extending recent quantitative spatial economics models, I analyze these counteracting forces. I find that when the local damages from pollution are not internalized by the industry and workers react to low air quality through migration, the largest cities can be too small. As a result, an optimal set of policies imposes higher emission taxes in these locations relative to the rest of the country. I estimate the model using French data and find that current policies impose higher costs of emissions in larger cities but raising them even higher could achieve welfare gains.

• March 28th, 2023 : Enrique Ide (IESE) - “Cross-Market Mergers with Common Customers: When (and Why) Do They Increase Negotiated Prices?”

The effects of cross-market mergers of upstream suppliers in the presence of common customers are very controversial. Some argue that products will be substitutes for intermediaries. Others say that because products are complements to customers, they must also be complements for intermediaries. I contribute to this debate by showing that two products can be complements for customers but substitutes in profits for intermediaries. The reason is that they can be substitutable in the traffic generated for other items in intermediaries’ lineups. This result leads to novel antitrust recommendations and can explain why cross-market mergers of hospitals have increased insurers’ prices.

• March 23th, 2023 : Maria Margarita Lopez Forero (U. Evry) - “Productivity Slowdown and Tax Havens: where is measured value creation?”

Based on French firm-level data, we evaluate the contribution of the micro-level profitshifting –through tax haven foreign direct investments– to the aggregate productivity slowdown measured in France. We show that firm measured productivity in France declines over the years following the establishment in a tax haven, with an average estimated drop by 3.5% in apparent labor productivity. To isolate the contribution of multinational enterprises’ (MNEs) tax optimization to the decline in productivity, we then exploit the 2006 Cadbury-Schweppes decision of the European Court of Justice limiting the extent to which member States can counter European MNEs’ tax planning strategies. We find that multinational groups benefiting from that loosening of the legal constraints do exhibit a lower labor productivity following that ruling. Finally, given these firms’ weight, our results imply an annual loss of 5.7% in terms of the aggregate annual labor productivity growth.

• March 21th, 2023 : Thomas Epper (CNRS-IESEG) - “The Fundamental Properties, the Stability and the Predictive Ability of Distributional Preferences”

Social preferences play an important role in a large variety of domains, yet knowledge about their distribution in the broader population is still scarce. In this paper, we study the fundamental properties, the stability and the predictive ability of distributional preferences in four different samples drawn from the general population. We characterize preference heterogeneity using a Bayesian nonparametric clustering method that allows to segregate individuals into distinct types based ontheir behavioral similarities. The method (i) does not ex-ante assume the existence of specific preference types nor does it require characterization of the preference functions, it (ii) allows for the full spectrum of behavioral heterogeneity in the population (ranging from a single representative agent to all individuals being different), and it (iii) makes the tradeoff between parsimony and descriptive accuracy explicit by penalizing the increased complexity from adding new types. In all our four data sets, we identify three fundamentally distinct and empirically relevant behavioral types: a large group of inequality averse individuals, a somewhat smaller, but still large group of altruistic individuals, and a minority of predominantly selfish individuals. This preference characterization is strikingly stable over time, and it is robust across all data sets. We also demonstrate that our type characterization of behavioral heterogeneity has excellent predictive ability: it predicts behavior out-of-sample substantially better than a representative agent model, but it does only perform slightly worse than a model that permits all individuals to differ. Finally, we contrast these results with predictions obtained from a machine learning algorithm,and show that the out-of-sample predictive ability of our type-based model is considerably better than the predictive ability of the machine learning approach.

• March 14th, 2023 : Daniel Heyen (TU Kaiserslautern) - “Balancing the risk of tipping: Early Warning Systems from detection to management”

Many socio-ecological systems are expected to collapse once pressure exceeds a tipping point. As the exact location of tipping points is almost always unknown, a recent literature has focused on the detection of early warning signals (EWS) of tipping. We demonstrate the necessary steps to operationalize EWS for ecosystem management, shifting the focus from detecting EWS to using them. In a stylized ecosystem model that can generate EWS, we study early warning systems that consist of a tipping indicator (e.g. autocorrelation) and a trigger value. The trigger value determines the rate of false positive and false negative warnings and allows to balance the risk of tipping. Our framework complements the emerging EWS knowledge in the natural sciences with a better understanding of how, when, and why EWS improve management. We further uncover a tension between better information and increased risk, highlighting that EWS may increase the risk of collapse.

• Tuesday, February 14th, 2023 : Eve Colson-Sihra (Hebrew U.) - “Market Structure and Inequality: Welfare Implications of Products Bans”

We study the distributional effects on consumers and firms of regulatory interventions that impact market structure. We do this in the context of the noodles market in India, where the largest manufacturer was found in non-compliance with nutritional standards and banned from the market for six months. We show substantial market heterogeneity in consumers' responses across income categories and the presence of negative spillovers to competitors. We identify demand and supply responses to the intervention by estimating a structural model of consumer and firm behavior. Through the calculation of counterfactuals, the model allows us to analyze if firms' responses were driven by changes in competition (e.g., the remaining firms face less competition after the intervention), changes in consumer behavior (e.g., consumers abandoning the entire category rather than just the targeted firm), or a combination of the two. Of particular interest is the analysis of whether higher- or lower-income consumers were more likely to respond to the ban by substituting away from the focal product category.

• Tuesday, January 24th, 2023 : Jean-Philippe Nicolaï (Grenoble INP - GAEL) - “Lobbying On Environmental Standards Under Deep Trade Agreements”

Après des décennies de réductions tarifaires progressives, il reste peu d'obstacles classiques au commerce international. En conséquence, l'objectif des nouveaux accords commerciaux est passé de concessions tarifaires supplémentaires à l'harmonisation d'autres réglementations ayant une incidence sur le commerce entre les pays. Nous construisons un modèle théorique pour analyser comment cette intégration commerciale croissante affecte la réglementation environnementale et l'activité de lobbying dans un cadre stratégique de deux pays. Nous dérivons d'abord des expressions analytiques pour les niveaux de réglementation optimaux dans divers scénarios commerciaux. Nos résultats montrent de fortes incitations à la coopération réglementaire internationale, mais les effets peuvent être réducteurs de bien-être en présence d'entreprises politiquement influentes. Ensuite, nous étendons le modèle en considérant les efforts de lobbying endogènes. Une intégration commerciale profonde tend à augmenter le lobbying par rapport à un accord conventionnel peu profond et peut inciter les lobbies des différents pays à se coordonner, ce qui est toujours préjudiciable au bien-être. S'engager à une harmonisation réglementaire parfaite par opposition à une convergence partielle peut améliorer le bien-être en affaiblissant l'influence des lobbies. Cependant, cela est toujours en contradiction avec l'objectif du décideur politique.

• Tuesday, January 17th, 2023 : Anna Ignatenko (NHH) - “Countervailing Power of Firms in International Trade”

La variation des prix entre les acheteurs au sein des catégories de produits est généralement expliquée par la variation de la qualité dans le commerce international. En utilisant des descriptions de produits uniquement détaillées, je contrôle la qualité et étudie les mécanismes de pouvoir de marché de la variation des prix entre les acheteurs. Je développe un modèle de commerce, dans lequel les acheteurs et les vendeurs diffèrent en productivité et peuvent avoir un pouvoir de marché pour fixer les prix. Ce modèle prédit des schémas différentiels de variation des prix en fonction de la productivité des acheteurs en cas d'oligopole, d'oligopsone et de négociation bilatérale dans un environnement de commerce international standard. En testant ces prédictions, je trouve que, dans la plupart des marchés, la variation des prix est cohérente avec la discrimination des prix par les vendeurs oligopolistiques qui facturent des marges plus faibles aux acheteurs plus productifs. J'identifie le rôle des options extérieures de l'acheteur dans ce résultat, séparément des économies d'échelle, des prix de transfert et de la capacité de négociation. Ces résultats impliquent que les grandes entreprises productives bénéficient davantage de la libéralisation du commerce en raison de leur capacité à réduire davantage les prix des intrants en menaçant de recourir à d'autres fournisseurs.

• Tuesday, January 10th, 2023 : Pierre Levasseur (INRAE-SADAPT) - “The association between meat consumption and body mass index varies according to the socioeconomic status in a representative sample of French adults”

Dans un contexte de plaidoyer croissant pour la réduction de la consommation de viande dans les pays occidentaux, nous vérifions si les populations ayant un faible statut socio-économique (SES) sont plus susceptibles de remplacer la viande par des alternatives moins saines, ce qui pourrait réduire la qualité du régime alimentaire et avoir des effets négatifs sur les résultats de santé tels que la prise de poids. Nous avons effectué des régressions linéaires multivariées axées sur les tendances spécifiques au SSE dans l'association entre la consommation de viande et l'IMC, et entre la consommation de viande et la consommation de groupes d'aliments autres que la viande. Nous nous sommes concentrés sur la population adulte française en utilisant une enquête nationale représentative des ménages sur la santé et la nutrition (n=1 300) collectée en 2015. Nous avons constaté que parmi les ménages à faible revenu, un jour de moins de consommation de viande par mois avait tendance à être associé à un IMC individuel plus élevé (0,074±0,039 kg/m²), en contraste significatif avec l'association inverse trouvée dans les ménages plus riches (combinant les groupes à revenu moyen et élevé). Cette différence dans la relation entre la viande et l'IMC, basée sur le revenu, était particulièrement forte chez les hommes, les jeunes et les adultes ruraux. Les ménages à faible revenu et à revenu élevé avaient également des habitudes alimentaires différentes associées à une consommation de viande plus élevée : parmi les ménages à faible revenu, une consommation de viande plus faible était associée à une consommation plus élevée de crème glacée et de sorbet, tandis que parmi les groupes à revenu plus élevé (>1 751 €/mois), une consommation de viande plus faible était associée à une consommation plus faible d'aliments et de boissons riches en graisses et en sucres, ainsi que de fromage. Notre étude est la première à montrer que le statut socioéconomique modifie la relation entre le niveau de consommation de viande et l'IMC dans un échantillon représentatif au niveau national.