NAPP Clotilde

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.

No summary available.

Gender differences in math performance are now small in developed countries and they cannot explain on their own the strong under-representation of women in math-related fields. This latter result is however no longer true once gender differences in reading performance are also taken into account. Using individual-level data on 300,000 15-year-old students in 64 countries, we show that the difference between a student performance in reading and math is 80% of a standard deviation larger for girls than boys, a magnitude considered as very large. When this difference is controlled for, the gender gap in students' intentions to pursue math-intensive studies and careers is reduced by around 75%, while gender gaps in self-concept in math, declared interest for math or attitudes towards math entirely disappear. These latter variables are also much less able to explain the gender gap in intentions to study math than is students' difference in performance between math and reading. These results are in line with choice models in which educational decisions involve intra-individual comparisons of achievement and self-beliefs in different subjects as well as cultural norms regarding gender. To directly show that intra-individual comparisons of achievement impact students' intended careers, we use differences across schools in teaching resources dedicated to math and reading as exogenous variations of students comparative advantage for math. Results confirm that the comparative advantage in math with respect to reading at the time of making educational choices plays a key role in the process leading to women's under-representation in math-intensive fields.

We study the effects of the presence of a negative stereotype on the formation of self-confidence and on decision-making in achievement-related situations. We take into account not only consumption utility but also psychological utility (ex-ante ego utility and ex-post disappointment/elation). We show that any stereotype of lower ability (in the form of biased interpretation of success and failure in terms of ability) leads to gaps in confidence, in participation in risky/ambitious options and in performance. Furthermore, we show how the stereotype survives and even gets reinforced. Considering gender and mathematics, we are able to explain the lower self-confidence of girls in mathematics, their underrepresentation in STEM fields, as well as their choices of less ambitious options and lower performance.

While gender gaps in average math performance are now close to zero in developed countries, women are still strongly underrepresented among math high performers (1). This gender gap contributes to the underrepresentation of women in math and science in higher education and to their subsequent worse position in the labor market (2, 3). With the roles of nature and nurture (4–6) on gender performance gaps having been debated for more than a century, research in the 1990s and 2000s (7–9) suggested a cultural origin, relating gender gaps in math to measures of countries' gender inequality. However, with more recent studies (10–12) having shown that this relation is weak, today we have no clearly identified relationship between countries' socioeconomic or cultural environment and the gender gap in math. We relate below gender gaps in math to societal inequalities that are not directly related to gender. We find a strong and robust relationship and provide tests suggesting that it is causal: Countries that are generally more egalitarian, or that have institutions more conductive to equality, have a lower gender performance gap in math, suggesting that this gap is partly shaped by more general societal inequalities.

We present a theoretical model of health beliefs and behaviors that explicitly takes into account the emotional impact of possible bad news (i.e., illness), ex-ante in the form of anxiety and ex-post in the form of disappointment. Our model makes it possible to explain (simultaneously) a number of anomalies such as ’low’ testing rates, heterogeneous perceptions of risk levels, underestimation of health risk, ostriches and hypochondriacs, over-use and under-use of health services, patient preference for information when relatively certain of not being ill, yet avoiding information when relatively certain of being ill, etc. Our model matches observed patterns both in health beliefs and health behaviors and irrational health beliefs and behaviors can be characterized as the optimal response under a given structure of emotions and preferences.

We analyze a model with two types of agents: standard agents and gurus, i.e. agents who have the ability to influence the other investors. Gurus announce their beliefs and act accordingly. Each investor has a preferred guru and follows his recommendations. Prices are determined through a classical Walras mechanism. Gurus are strategic: they take into account the impact of their announced beliefs on the other agents, hence on prices. At the Nash equilibrium, this leads to beliefs heterogeneity, to a positive correlation between optimism and risk aversion and to higher risk premia. The impact is stronger on the riskier assets.

We discuss Oster et al.’s (2013) model and propose an alternative model of optimal expectations to accommodate data on genetic testing.

We address the problem of a social planner who, as in Weitzman (2001), gathers data on experts’ discount rates and wants to infer the socially efficient consumption discount rate. We propose an ‘equilibrium approach’ and we analyse the expression and the properties of the resulting ‘equilibrium discount rate’. We compare our expression for the discount rate with the different expressions that have been previously proposed in the literature. We analyse the impact of shifts in the distributions of experts discount rates. Finally, we apply our approach to Weitzman (2001)’s data to propose discount rates for public sector Cost-Bene…t Analysis, in particular for the long term.

We revisit the model proposed by Gollier and Muermann (see Gollier, C. and A. Muermann, 2010, Optimal choice and beliefs with exante savoring and ex-post disappointment, Management Sci., 56, 1272-1284, hereafter GM). In GM, for a given lottery, agents form anticipated expected payoffs and the set of possible anticipations is assumed to be exogenously fixed. We rather propose sets of possible anticipations which are endogenously determined. This permits to compare and evaluate in a consistent manner lotteries with different supports and to revisit the portfolio choice problem. We obtain new conclusions and interesting insights. Our extended model can rationalize a variety of empirically observed puzzles like a positive demand for assets with negative expected returns, preference for skewed returns and under-diversification of portfolios.

In this paper we analyse the risk attitude of a group of heterogenous agents and we develop a theory of comparative collective risk tolerance. In particular, we characterize how shifts in the distribution of individual levels of risk tolerance affect the representative agent's degree of risk tolerance. In the model with efficient risk - sharing and two agents (e.g. a household) with isoelastic preferences we show that an increase of the level of risk tolerance of one of the agents might have an ambiguous impact on the aggregate level of risk tolerance. the latter increases for some levels of aggregate wealth while it decreases for other levels of aggregate wealth. Specifically, there are two possible shapes for aggregate risk tolerance as a function of the risk tolerance level of one of the agents: increasing curve or increasing then decreasing curve. For more general populations we characterize the effect of first order like shifts (individual levels of risk tolerance more concentrated on high values) and second order like shifts (more dispersion on individual levels of risk tolerance) on the collective level of risk tolerance. We also evaluate how shifts in the distribution of individual levels of risk tolerance impact the collective level of risk tolerance in a framework with exogenous egalitarian sharing rules. Our results permit to better characterize differences in risk taking behavior between groups and individuals and among groups with different distribution of risk preferences.

Kimball (1990) established that income risk increases the marginal propensity to consume if and only if absolute prudence is decreasing. We characterize decreasing and increasing multivariate prudence and we show that a multidimensional risk increases the marginal propensity to consume if and only if a matrix-measure of multivariate prudence decreases with wealth, in the sense that its derivative is negative-de…nite.

Why do investors keep different opinions even though they learn from their own failures and successes? Why do investors keep different opinions even though they observe each other and learn from their relative failures and successes? We analyze beliefs dynamics when beliefs result from a very general learning process that favors beliefs leading to higher absolute or relative utility levels. We show that such a process converges to the Nash equilibrium in a game of strategic belief choices. The asymptotic beliefs are subjective and heterogeneous across the agents. Optimism (resp. overconfidence) as well as pessimism (resp. doubt) both emerge from the learning process. Furthermore, we obtain a positive correlation between pessimism (resp. doubt) and risk-tolerance. Under reasonable assumptions, beliefs exhibit a pessimistic bias and, as a consequence, the risk premium is higher than in a standard setting.

Kimball (1990a,b) established that income risk increases the marginal propensity to consume if and only if absolute prudence decreases. We characterize decreasing and increasing multivariate prudence and show that a multidimensional risk increases the marginal propensity to consume if and only if absolute prudence decreases with wealth, in the sense that its derivative is negative-definite.

In this paper we extend the theory of precautionary saving to the case in which uncertainty is multidimensional and we develop a matrix-measure of multivariate prudence. Furthermore, we characterize comparative prudence, decreasing and increasing prudence, the effect of uncertainty on the marginal propensity to consume out of wealth, and the Drèze-Modigliani substitution effect in this multivariate setting. We also characterize the concept of multivariate downside risk aversion as a multivariate preference for harm disaggregation. We show that our definition is equivalent to a positive precautionary saving motive. We propose an alternative measure of the intensity of downside risk aversion and show that this measure is useful in understanding several economic problems that involve multivariate preferences.

We study comparative statics of Nth-degree risk increases within a large class of problems that involve bidimensional payoffs and additive or multiplicative risks. We establish necessary and sufficient conditions for unambiguous impact of Nth-degree risk increases on optimal decision making. We develop a simple and intuitive approach to interpret these conditions : novel notions of directional Nth-degree risk aversion that are characterized via preferences over lotteries.