Frédéric Dufourt

Chercheur ,  Aix-Marseille Université , Faculté d'économie et de gestion (FEG)

Macroéconomie, économie du travail et économie internationale
Dufourt
Statut
Professeur des universités
Domaine(s) de recherche
Macroéconomie
Thèse
2001, University Paris I Panthéon-Sorbonne
Téléchargement
CV
Contact
frederic.dufourt[at]univ-amu.fr
+33(0)4 13 55 25 46
Adresse

AMU - AMSE
5-9 Boulevard Maurice Bourdet, CS 50498
​13205 Marseille Cedex 1

Site
http://sites.google.com/site/econdufourt/
Résumé When can exogenous changes in beliefs generate endogenous fluctuations in rationalexpectation models? We analyze this question in the canonical one-sector and two-sector models of the business cycle with increasing returns to scale. A key feature of ouranalysis is that we express the uniqueness/multiplicity condition of equilibirum pathsin terms of restrictions on five critical and economically interpretable parameters: theFrisch elasticities of the labor supply curve with respect to the real wage and to themarginal utility of wealth, the intertemporal elasticity of substitution in consumption,the elasticity of substitution between capital and labor, and the degree of increasingreturns to scale. We obtain two clear-cut conclusions: belief-driven fluctuations cannotexist in the one-sector version of the model for empirically consistent values for thesefive parameters. By contrast, belief-driven fluctuations are a robust property of thetwo-sector version of the model—with differentiated consumption and investmentgoods—, as they now emerge for a wide range of parameter values consistent withavailable empirical estimates. The key ingredients explaining these different outcomesare factor reallocation between sectors and the implied variations in the relative priceof investment, affecting the expected return on capital accumulation.
Mots clés Income effect, Expectations, Endogenous fluctuations, Belief-driven business cycles
Publication HAL Google Scholar
Résumé We use a distinctive methodology that leverages a fixed population of Twitter users located in France to gauge the mental health effects of repeated lockdown orders. To do so, we derive from our population a mental health indicator that measures the frequency of words expressing anger, anxiety and sadness. Our indicator did not reveal a statistically significant mental health response during the first lockdown, while the second lockdown triggered a sharp and persistent deterioration in all three emotions. Our estimates also show a more severe deterioration in mental health among women and younger users during the second lockdown. These results suggest that successive stay-at-home orders significantly worsen mental health across a large segment of the population. We also show that individuals who are closer to their social network were partially protected by this network during the first lockdown, but were no longer protected during the second, demonstrating the gravity of successive lockdowns for mental health.
Mots clés Mental health, Twitter data, Well-being, Lockdown, COVID-19
Publication HAL Google Scholar
Résumé We revisit the canonical policy of eliminating capital taxation by increasing labor taxation in a endogenous-labor, heterogeneous-agent model with income and wealth heterogeneity, when the government is subject to a strict (per-period) balanced-budget constraint. By contrast with its non-budget neutral equivalent-associated with a constant tax rate over time and a permanent increase in the level of public debt-we show that the obtained endogenous path for the labor tax rate is sharply increasing in the initial period and decreasing over time. The policy then generates a deeper recession in the short-run and a greater expansion in the long-run, as well as a smaller decline in wealth inequality associated with a reduced incentive to save for precautionary motives. Overall, the policy still generates significant losses in average welfare.
Mots clés Wealth Redistribution, Heterogeneous agents, Tax Composition, Capital Tax Cut, Fiscal policy
Publication HAL Google Scholar
Résumé We investigate the extent to which standard one sector RBC models with positive externalities and variable capacity utilization can account for the large hump-shaped response of output when the model is submitted to a pure sunspot shock. We refine the Benhabib and Wen (2004) model considering a general type of additive separable preferences and a general production function. We provide a detailed theoretical analysis of local stabilities and local bifurcations as a function of various structural parameters. We show that, when labor is infinitely elastic, local indeterminacy occurs through Flip and Hopf bifurcations for a large set of values for the elasticity of intertemporal substitution in consumption, the degree of increasing returns to scale and the elasticity of capital-labor substitution. Finally, we provide a detailed quantitative assessment of the model and conclude with mixed results. We show that although the model is able theoretically to generate a hump-shaped dynamics of output following an i.i.d. sunspot shock under realistic parameter values, the hump is too persistent for the model to be considered fully satisfactory from an empirical point of view.
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Résumé Economies with oligopolistic markets are prone to inefficient sunspot fluctuations triggered by autonomous changes in firms equilibrium conjectures. A well-designed taxation-subsidization scheme can eliminate these fluctuations by coordinating firms in each sector on a single equilibrium, left unaffected. The optimal taxation scheme must select the number of active firms that makes the best trade-off (in terms of consumer welfare) between the markup and the scale inefficiency distortions. Implementing such stabilization policy leads to significant welfare gains, attributable to an “efficient stabilization effect,” typically ignored in usual computations of the welfare costs of fluctuations.
Mots clés Economie quantitative
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Résumé We analyze the conditions of emergence of a twin banking and sovereign debt crisis within a monetary union in which: (i) the central bank is not allowed to provide direct financial support to stressed member states or to play the role of lender of last resort in sovereign bond markets, and (ii) the responsibility of fighting against large scale bank runs, ascribed to domestic governments, is ensured through the implementation of a financial safety net (banking regulation and government deposit guarantee). We show that this broad institutional architecture, typical of the Eurozone at the onset of the financial crisis, is not always able to prevent the occurrence of a twin banking and sovereign debt crisis triggered by pessimistic investors’ expectations. Without significant backstop by the central bank, the financial safety net may actually aggravate, instead of improve, the financial situation of banks and of the government.
Mots clés Government deposit guarantee, Govern, Financial safety net, Liquidity regulation, Sovereign debt crisis, Banking crisis, Bank runs
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Résumé We analyze a version of the Benhabib and Farmer (1996) two-sector model with sector-specific externalities in which we consider a class of utility functions inspired from the one considered in Jaimovich and Rebelo (2009) which is flexible enough to encompass varying degrees of income effect. First, we show that local indeterminacy and sunspot fluctuations occur in 2-sector models under plausible configurations regarding all structural parameters—in particular regarding the intensity of income effects. Second, we prove that there even exist some configurations for which local indeterminacy arises under any degree of income effect. More precisely, for any given size of income effect, we show that there is a non-empty range of values for the Frisch elasticity of labor and the elasticity of intertemporal substitution in consumption such that indeterminacy occurs. This contrasts with the results obtained in one-sector models in both Nishimura et al. (2009), in which it is shown that indeterminacy cannot occur under either GHH and KPR preferences, and in Jaimovich (2008) in which local indeterminacy only arises for intermediary income effects.
Mots clés Sector-specific externalities, Sunspots, O41, Infinite-horizon two-sector model, Indeterminacy, Income and substitution effects, Social and Behav Sciences, Economics, Game Theory, Economic Theory/Quantitative Economics/Mathematical Methods, Economic Growth, E32, C62
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Résumé We analyze sunspot-driven fluctuations in the standard two-sector \RBC\ model with moderate increasing returns to scale and generalized no-income-effect preferences à la Greenwood, Hercovitz and Huffman [13]. We provide a detailed theoretical analysis enabling us to derive relevant bifurcation loci and to characterize the steady-state local stability properties as a function of various structural parameters. We show that local indeterminacy occurs through flip and Hopf bifurcations for a large set of values for the elasticity of intertemporal substitution in consumption, provided that the labor supply is sufficiently inelastic. Finally, we provide a detailed quantitative analysis of the model. Computing, on a quarterly basis, a new set of empirical moments related to two broadly defined consumption and investment sectors, we are able to identify, among the set of admissible calibrations consistent with sunspot equilibria, the ones that provide the best fit of the data. The model properly calibrated solves several empirical puzzles traditionally associated with two-sector \RBC\ models.
Mots clés Two-sector model, Sunspots, Sector-specific externalities, Real business cycles, Indeterminacy
Publication HAL Google Scholar
Résumé We study the implications of constant money growth rules on the stability properties of the equilibrium, in economies where the agents are subject to a partial cash-in-advance constraint applying simultaneously to consumption and investment purchases. By reference to similar models in which the liquidity constraint applies only to consumption, we show that the inclusion of investment has dramatic, but contrasting, effects on the range of values giving rise to indeterminacy. First, it increases strongly a lower bound on the share of purchases requiring cash, below which the steady state is always indeterminate. Second, it creates a higher bound on this share, above which the steady state is always determinate. In this context, the steady-state value of the velocity of money becomes a crucial parameter for gauging whether constant money growth rules may be stabilizing or destabilizing for the economy.
Mots clés Cash-in-advance, Indeterminacy, Business Cycles
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Résumé Free entry equilibria are usually characterized by the zero profit condition. We plead instead for a strict application of the Nash equilibrium concept to a symmetric simultaneous game played by actual and potential entrants, producing under decreasing average cost. Equilibrium is then typically indeterminate, with a number of active firms varying between an upper bound imposed by profitability and a lower bound required by sustainability. We use a canonical model with strategies represented by prices, although covering standard regimes of quantity and price competition, to show that in equilibrium the critical (profit maximizing) price must lie between the break-even and the limit prices.
Mots clés Free entry equilibrium, Zero-profit condition, Oligopolistic competition
Publication HAL Google Scholar
Résumé When can exogenous changes in beliefs generate endogenous fluctuations in rational expectation models? We analyze this question in the canonical one-sector and two-sector models of the business cycle with increasing returns to scale. A key feature of our analysis is that we express the uniqueness/multiplicity condition of equilibirum paths in terms of restrictions on five critical and economically interpretable parameters: the Frisch elasticities of the labor supply curve with respect to the real wage and to the marginal utility of wealth, the intertemporal elasticity of substitution in consumption, the elasticity of substitution between capital and labor, and the degree of increasing returns to scale. We obtain two clear-cut conclusions: belief-driven fluctuations cannot exist in the one-sector version of the model for empirically consistent values for these five parameters. By contrast, belief-driven fluctuations are a robust property of the twosector version of the model-with differentiated consumption and investment goods-, as they now emerge for a wide range of parameter values consistent with available empirical estimates. The key ingredients explaining these different outcomes are factor reallocation between sectors and the implied variations in the relative price of investment, affecting the expected return on capital accumulation.
Mots clés Belief-driven business cycles, Endogenous fluctuations, Expectations, Income effect
Télécharger HAL Google Scholar
Résumé We use a distinctive methodology that leverages a fixed population of Twitter users located in France to gauge the mental health effects of repeated lockdown orders. To do so, we derive from our population a mental health indicator that measures the frequency of words expressing anger, anxiety and sadness. Our indicator did not reveal a statistically significant mental health response during the first lockdown, while the second lockdown triggered a sharp and persistent deterioration in all three emotions. Our estimates also show a more severe deterioration in mental health among women and younger users during the second lockdown. These results suggest that successive stay-at-home orders significantly worsen mental health across a large segment of the population. We also show that individuals who are closer to their social network were partially protected by this network during the first lockdown, but were no longer protected during the second, demonstrating the gravity of successive lockdowns for mental health.
Mots clés Mental health, Twitter data, Well-being, Lockdown, COVID-19
Publication Télécharger HAL Google Scholar
Résumé Macroeconomic models in which exogenous, self-fulfilling changes in expectations play a significant role in output fluctuations are often discarded on two claims: they require implausible calibrations of structural parameters and they are enable to account for several empirical features associated with demand shocks. We show that these claims are only valid to the extent that they are applied to one-sector models. In contrast, we prove that two-sector models allow the existence of self-fulfilling prophecies for a large set of empirically realistic values for all the structural parameters, and that a two-sector model submitted to sunspot shocks can account not only for all the standard stylized facts associated with demand shocks, but also for other dimensions of the business cycle that standard RBC-type models cannot explain.
Mots clés Indeterminacy, One and two-sector models, Endogenous labor supply, Income effect, Productive externalities, Permanent and transitory shocks
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Résumé We revisit the canonical policy of eliminating capital taxation by increasing labor taxation in a endogenous-labor, heterogeneous-agent model with income and wealth heterogeneity, when the government is subject to a strict (per-period) balancedbudget constraint. By contrast with its non-budget neutral equivalent-associated with a constant tax rate over time and a permanent increase in the level of public debt-we show that the obtained endogenous path for the labor tax rate is sharply increasing in the initial period and decreasing over time. The policy then generates a deeper recession in the short-run and a greater expansion in the long-run, as well as a smaller decline in wealth inequality associated with a reduced incentive to save for precautionary motives. Overall, the policy still generates significant losses in average welfare.
Mots clés Wealth Redistribution, Heterogeneous agents, Tax Composition, Capital Tax Cut, Fiscal policy
Télécharger HAL Google Scholar
Résumé We analyze a version of the Benhabib and Farmer [3] two-sector model with sector-specific externalities in which we consider a class of utility functions inspired from the one considered in Jaimovich and Rebelo [14] which is flexible enough to encompass varying degrees of income effect. First, we show that local indeterminacy and sunspot fluctuations occur in 2-sector models under plausible configurations regarding all structural parameters – in particular regarding the intensity of income effects. Second, we prove that there even exist some configurations for which local indeterminacy arises under any degree of income effect. More precisely, for any given size of income effect, we show that there is a non-empty range of values for the Frisch elasticity of labor and the elasticity of intertemporal substitution in consumption such that indeterminacy occurs. This contrasts with the results obtained in one-sector models in both Nishimura et al. [19], in which it is shown that indeterminacy cannot occur under either GHH and KPR preferences, and in Jaimovich [13] in which local indeterminacy only arises for intermediary income effects.
Mots clés Indeterminacy, Sunspots, Income and substitution effects, Sector-specific externalities, Infinite-horizon two-sector model
Télécharger HAL Google Scholar
Résumé We analyze sunspot-driven fluctuations in the standard two-sector RBC model with moderate increasing returns to scale and generalized no-income-effect preferences à la Greenwood, Hercovitz and Huffman [13]. We provide a detailed theoretical analysis enabling us to derive relevant bifurcation loci and to characterize the steady-state local stability properties as a function of various structural parameters. We show that local indeterminacy occurs through flip and Hopf bifurcations for a large set of values for the elasticity of intertemporal substitution in consumption, provided that the labor supply is sufficiently inelastic. Finally, we provide a detailed quantitative analysis of the model. Computing, on a quarterly basis, a new set of empirical moments related to two broadly defined consumption and investment sectors, we are able to identify, among the set of admissible calibrations consistent with sunspot equilibria, the ones that provide the best fit of the data. The model properly calibrated solves several empirical puzzles traditionally associated with two-sector RBC models.
Mots clés Indeterminacy, Sunspots, Two-sector model, Sector-specific externalities, Real business cycles cycles
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Résumé We analyze local indeterminacy and sunspot-driven fluctuations in the standard two-sector model with additively separable preferences. We provide a detailed theoretical analysis enabling us to derive relevant bifurcation loci and to characterize the steady-state local stability properties as a function of various structural parameters influencing the degree of increasing returns to scale, the amount of intertemporal substitution in consumption, and the elasticity of the aggregate labor supply curve. On the theoretical side, we prove the existence of both a flip and a Hopf bifurcation locus in the corresponding parameter space. We also show that local indeterminacy can be obtained under any labor supply elasticity or under an arbitrarily low elasticity of intertemporal substitution in consumption. On the empirical side, we find that indeterminacy and sunspot fluctuations are robust features of two-sector models, prevailing for most empirically plausible calibrations for these parameters.
Mots clés Indeterminacy, Sector-specific externalities, Real business cycles, Sunspots, Two-sector model
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Résumé We introduce Large Scale Asset Purchases (LSAPs) in a New-Keynesian DSGE model that features distinct mortgage and corporate loan markets. We show that following a significant disruption of financial intermediation, central-bank purchases of mortgage-backed securities (MBS) are uniformly less effective at easing credit market conditions and stabilizing economic activity than outright purchases of corporate bonds. Moreover, the size of the effects crucially depends on the extent to which credit markets are segmented, i.e. to which a "portfolio balance channel" is at work in the economy. More segmented credit markets imply larger, but more local effects of particular asset purchases. With strongly segmented credit markets, large scale purchases of MBS are useful to stabilize the housing market but do little to mitigate the contractionary effect of the crisis on employment and output.
Mots clés Financial frictions, Mortgage-backed securities MBS, Corporate bonds, Unconventional monetary policy, Large scale asset purchases LSAPs, Portfolio balance channel, Credit spreads
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Résumé We analyze sunspot-driven fluctuations in the standard 2-sector RBC model with moderate increasing returns to scale. We provide a detailed theoretical analysis enabling us to derive relevant bifurcation loci and to characterize the steady-state local stability properties as a function of various structural parameters. With GHH preferences, we show that local indeterminacy occurs through flip and Hopf bifurcations for a large set of values of the elasticity of intertemporal substitution in consumption if the labor supply is sufficiently inelastic. With additively-separable preferences, we prove that local indeterminacy occurs through flip and Hopf bifurcations for any value of the elasticity of the labor supply, and can even be compatible with an arbitrarily low elasticity of intertemporal substitution in consumption. Finally, we provide a detailed quantitative analysis of the model. Computing, on a quarterly basis, a new set of empirical moments related to two broadly defined consumption and investment sectors, we are able to identify, among the set of admissible calibrations consistent with sunspot equilibria, the ones that provide the best fit of the data. The model properly calibrated solves several empirical puzzles traditionally associated with 2-sector RBC models.
Mots clés Indeterminacy, Sunspots, Two-sector model, Sector-specific externalities, Real business cycles
Télécharger HAL Google Scholar