Publications des chercheurs de PSE

Grand commis de l’État, réformateur, caïd, plusieurs fois ministre, Grand vizir de Lamine Bey, déporté par les Français, prisonnier de Bourguiba, Mohamed-Salah Mzali (1896-1984) est un homme de pouvoir. Il est aussi le premier Tunisien à soutenir une thèse de doctorat en économie après une brillante scolarité à Sadiki et à Carnot. Historien, érudit, sauveur des archives de Khérédine Pacha, il contribuera à inscrire ce dernier dans l’historiographie nationale.La première partie de cet ouvrage reproduit Au fil de ma vie, les mémoires de l’écrivain méconnu, imprégné de culture classique et plume singulière de la littérature tunisienne. Elle retrace les étapes d’un parcours d’exception, de l’enfance jusqu’à une retraite tourmentée après une fulgurante carrière. Le ton, mesuré et tranchant, est à l’image de l’homme : habile séducteur, mais réservé face aux ors du sérail et sensible aux dérives de l’hybris. S’il finit écarté des centres du nouveau pouvoir, il n’en livre pas moins un témoignage « de bonne foi » au lecteur soucieux de saisir les soubresauts d’un siècle qu’il traverse tantôt en fin politique, tantôt en promeneur méditatif.Dans L’intellectuel et l’homme d’État, en deuxième partie, Elyès Jouini poursuit le travail entamé dans le premier volet largement enrichi de notes explicatives, et nous propose une deuxième œuvre qui procède à un rare décryptage et à une mise en contexte historique de l’homme et de l’œuvre.Il restitue fidèlement un personnage de grande envergure à l’histoire politique, sociale et culturelle de son siècle, tout en laissant entrevoir les paradoxes et les mutations d’une élite sur le point de céder la place, emportée par le flot de la décolonisation.Une riche iconographie, souvent inédite, offre un nouvel éclairage.Le livre est coédité par Cérès éditions- Beït al-Hikma et l’Institut de recherche sur le Maghreb contemporain (IRMC) Elyès Jouini est l’administrateur de l’Institut universitaire de France et professeur à l’Université Paris Dauphine-PSL où il est titulaire de la chaire Dauphine-UNESCO. Ancien élève de l’École normale supérieure de Paris, ses travaux sont à l’interface des sciences formelles et des sciences humaines et sociales. E. Jouini est membre correspondant de l’Académie tunisienne des sciences, des lettres et des arts. Préface de Kmar Bendana, professeure émérite d'histoire contemporaine à l'Université de La Manouba, chercheure associée à l'Institut de recherche sur le Maghreb contemporain.

This paper uses an original telepsychology European survey conducted by the EFPA (European Federation of Psychologists Associations) Project Group in e-Health between March 18th and May 5th, 2020, to consider online practices of psychologists. We set up evidence from France compared with other European countries. First, we observe that France is the European country where psychologists’ perception of the concept of online consultations is the worse. It goes through the lowest rate of specific training concerning online consultations. Also France is the European country where psychologists have the worse experience (after Belgium) with online consultations, prior to the COVID-19 outbreak. Second, we address the issue of determinants of the teleconsultation feelings. We take advantage of this survey panel of 13 European countries that allows us to consider within-country telepractice behaviour. Our results show that a specific training is a key factor for a positive feeling with the concept of online consultation practices. In addition, telepresence (feeling of being connected with one another) and positive overall experience capture the effect of the specific training. French psychologists differ from the other European countries telepsychologists by an absence of specific training effect on the feeling with online consultation that may be explained by the lack of specific training. However, as for European psychologists, French psychologists’ perception of telepractice depends on their level of telepresence and on their overall experience in telepractice.

We model a continuous-time economy with a continuum of investors who differ both in belief and time preference rate and analyze the impact of these heterogeneities on the behavior of financial markets. In particular, we allow the two types of heterogeneity to be correlated: a negative correlation means that the most optimistic agents are also the most patient ones. We fully characterize the risk-free rate which is procyclical and the market price of risk which is countercyclical. When the two types of heterogeneity are negatively correlated, the former is higher and the latter lower compared to the standard case. A negative correlation also leads to a higher market volatility. Moreover, we find that the trading volume increases with the variance of the belief heterogeneity distribution. Finally, the surviving agent of this economy is not necessarily the one who maximizes her utility over her lifetime: a shorter life might be more rewarding than a longer one.

In both arbitrage and utility pricing approaches, the fictitious completion appears as a powerful tool that permits to extend complete markets results to an incomplete markets framework. Does this technique permit to characterize the equilibrium pricing interval? This note provides a negative answer.

The so-called “gender-equality paradox” is the fact that gender segregation across occupations is more pronounced in more egalitarian and more developed countries. Some scholars have explained this paradox by the existence of deeply rooted or intrinsic gender differences in preferences that materialize more easily in countries where economic constraints are more limited. In line with a strand of research in sociology, we show instead that it can be explained by cross-country differences in essentialist gender norms regarding math aptitudes and appropriate occupational choices. To this aim, we propose a measure of the prevalence and extent of internalization of the stereotype that “math is not for girls” at the country level. This is done using individual-level data on the math attitudes of 300,000 15-y-old female and male students in 64 countries. The stereotype associating math to men is stronger in more egalitarian and developed countries. It is also strongly associated with various measures of female underrepresentation in math-intensive fields and can therefore entirely explain the gender-equality paradox. We suggest that economic development and gender equality in rights go hand-in-hand with a reshaping rather than a suppression of gender norms, with the emergence of new and more horizontal forms of social differentiation across genders.

I develop a continuous-time general equilibrium model with a continuum of states of the world and a continuum of agents endowed with heterogeneous beliefs. The model permits to analyze the interactions between financial markets and production. There is a single firm that faces convex adjustment costs and maximizes its terminal value. Equivalently, the firm uses decreasing returns to scale risk-return technology. The model is tractable and matches many of the empirical regularities in aggregate output and stock prices, such as a financial volatility that is higher than the macroeconomic volatility, skewness, kurtosis, short-term momentum, and volatility risk premium during recessions. All these aspects disappear when one assumes beliefs homogeneity or constant returns to scale. In particular, the impact of beliefs heterogeneity observed in endowment economies does not pertain when introducing production unless one assumes decreasing returns to scale in the risk-return technology. This paper was accepted by David Sraer, finance.

Consider a firm owned by shareholders with heterogeneous beliefs and discount rates who delegate to a manager the choice of a production plan. The shareholders and the manager can trade contingent claims in a complete asset market. Shareholders cannot observe the chosen production plan and design a compensation scheme so that at equilibrium the manager chooses the plan they prefer and reveals it truthfully. We show that at equilibrium (i) profit is maximized, (ii) the manager gets a constant share of production, (iii) she has no incentive to trade. We then show that such equilibrium exists if and only if the manager has the same belief and discount rate as the representative shareholder. This allows us to characterize the required characteristics of the manager as a function of shareholders' characteristics.

In the COVID-19 pandemic many countries required COVID certificates, proving vaccination, recovery, or a recent negative test, to access public and private venues. We estimate their effect on vaccine uptake for France, Germany, and Italy using counterfactuals constructed via innovation diffusion theory. The announcement of COVID certificates during summer 2021 were associatedalthough causality cannot be directly inferredwith increased vaccine uptake in France of 13.0 (95% CI 9.7-14.9) percentage points (p.p.) of the total population until the end of the year, in Germany 6.2 (2.6-6.9) p.p., and in Italy 9.7 (5.4-12.3) p.p. Based on these estimates, an additional 3979 (3453-4298) deaths in France, 1133 (−312-1358) in Germany, and 1331 (502-1794) in Italy were averted; and gross domestic product (GDP) losses of €6.0 (5.9-6.1) billion in France, €1.4 (1.3-1.5) billion in Germany, and €2.1 (2.0-2.2) billion in Italy were prevented. Notably, in France, the application of COVID certificates averted high intensive care unit occupancy levels where prior lockdowns were instated.

Consider a firm owned by shareholders with heterogeneous beliefs and run by a manager who chooses random production plans. Shareholders do not observe the chosen plan but only its realization. The financial market consists of assets contingent on production realizations. A contract for the manager specifies her compensation as a function of the firm's production and possibly some restrictions to trade in the financial market. Shareholders are unrestricted. We define a concept of equilibrium between the manager and shareholders such that the equilibrium production plan is unanimously preferred by the manager and the shareholders, markets clear and the manager has no incentive to cheat. We first analyze the properties of such equilibria and in particular show that the contract should restrict the manager from trading. We next provide a framework where such equilibria exist. We lastly study the properties of equilibrium compensations when shareholders have beliefs that can be ranked in terms of optimism towards the equilibrium plan. Specific attention is given to their departure from linear compensations.

All over the world, measures were taken to prevent the spread of COVID-19. Social distancing not only had a strong influence on mental health, but also on the organization of care systems. It changed existing practices, as we had to rapidly move from face-to-face contact to remote contact with patients. These changes have prompted research into the attitudes of mental healthcare professionals towards telepsychology. Several factors affect these attitudes: at the institutional and organizational level, but also the collective and personal experience of practitioners. This paper is based on an original European survey conducted by the EFPA (European Federation of Psychologists’ Associations) Project Group on eHealth in 2020, which allowed to observe the variability in perceptions of telepsychology between countries and mental healthcare professionals. This study highlights different variables that contributed to the development of attitudes, such as motivations, acquired experience, or training. We found the “feeling of telepresence”—which consists of forgetting to some extent that we are at a distance, in feeling together—and social telepresence in particular as main determinants of the perception and the practice of telepsychology.

Even though females currently outnumber males in higher education, they remain largely underrepresented in math-related fields of study, with no sign of improvement during the past decades. To better understand which students drive this underrepresentation, we use PISA 2012 data on 251,120 15-year-old students in 61 countries to analyse boys’ and girls’ educational intentions along the ability distribution on math assessment tests. We analyze the percentages of boys and girls intending to pursue math-related studies or careers as a function of math performance. First, we show that for both boys and girls, there is a positive and linear relation between the probability of intending to pursue math and math performance. Second, the positive relation is stronger among boys than among girls. In particular, the gender gap in student intentions to pursue math-related studies or careers is close to zero among the poorest performers in math and increases steadily with math performance. Third, as a consequence, the gender gap in math performance, to the detriment of girls, is larger among students intending to pursue math than in the general student population.