Portail HAL Paris School of Economics (PSE)
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Centrality measures in networks
No full textInternational audienceWe show that prominent centrality measures in network analysis are all based on additively separable and linear treatments of statistics that capture a node’s position in the network. This enables us to provide a taxonomy of centrality measures that distills them to varying on two dimensions: (i) which information they make use of about nodes’ positions, and (ii) how that information is weighted as a function of distance from the node in question. The three sorts of information about nodes’ positions that are usually used—which we refer to as “nodal statistics”—are the paths from a given node to other nodes, the walks from a given node to other nodes, and the geodesics between other nodes that include a given node. Using such statistics on nodes’ positions, we also characterize the types of trees such that centrality measures all agree, and we also discuss the properties that identify some path-based centrality measures
Into the Far West? Investigating Health Policy-Makers' Willingness to Adopt Decrementally Cost-Effective Innovations Using a DCE Approach
No full textIn a context of increasingly limited resources, a number of strategies, such as the adoption of decrementally cost-effective interventions (d-CEIs), which are both less clinically effective and less costly, could offer potential levers at enhancing both efficiency and equity in healthcare systems. These interventions are located in the SouthWest (S-W) quadrant of the cost-effectiveness plane, and have yet received little attention from researchers or HTA agencies as they are often perceived as per se "unethical" or "unacceptable", hence the reference sometimes made to the S-W quadrant as the 'Far West'. The purpose of our paper is to investigate policy-makers' willingness to adopt d-CEIs using a choice experiment. We use a two-stage pairwise DCE survey to elicit (i) preferences for d-CEIs' attributes in forced choices and (ii) adoption preferences, i.e. the determinants of d-CEIs' adoption (unforced choices). We investigate the effect (and trade-offs) between three attributes: health loss (very small to significant), reversibility defined as the possibility to switch back to usual care (from possible to hardly possible) and cost-savings (from 5% to 15% of a fixed budget). Such trade-offs are contextualized by using two sensitivity attributes: disease severity (low and moderate) and savings uncertainty (low and high). Our final sample consists of 180 respondents with 46.7% originating from France and the remaining respondents from other EU countries. All attributes' levels have a significant effect in the two decision stages. The "health loss" attribute dominates in the first stage followed by "reversibility": we calculate that decision-makers would require 28.3% increase of budget savings to be indifferent between a scenario of small versus significant health losses and 14.5% budget savings to be indifferent between a scenario of possible and hardly possible reversibility. In contrast, the "reversibility" attribute dominates in the second stage suggesting that anticipated regret may play a role in adoption decisions
Expectation Formation, Local Sampling and Belief Traps: A new Perspective on Education Choices
No full textLack of diversity in higher education is partly driven by long-run belief distortions about admission chances at elite colleges. We depart from the rational expectation framework and propose a simple model of expectation formation in which students estimate their admission chances by sampling a pool of given size τ of peers who previously applied to elite colleges. Assuming students consider peers with abil-ity as close as possible to their own, two types of inefficiencies arise in steady state: high-achieving disadvantaged students self-select out of elite colleges, and average students from advantaged families apply to elite colleges even though their true admission chances are null. We then explore the working of the model when students from several possibly dissimilar neighborhoods compete for the same positions, thereby highlighting externalities related to the comparative neighborhood com-positions. Several policy instruments such as quotas or the mixing of neighborhoods are considered
Inflation des prix alimentaires : quelles conséquences possibles pour les ménages modestes ?
No full textInternational audienceFood prices have been rising sharply for over a year now. The provisional results published by Insee in January 2023 show an increase of of 13.2% since January 2022, more than double the rise in the price index (+6%) and slightly slightly less than energy prices (+16%) [1]. Detailed data published by IRI show that price rises have particularly affected staple foods and "bottom-of-the-range bottom-of-the-cupboard" products, such as oils, rice, sugar or minced steaks [2]. Prices for "first-price" and private-label products are rising more sharply than national brands (+17.8% for the former and +11.6% for the latter the latter [3]), probably due to lower margins, which mean that the increase in more directly on the final price. The causes of these price rises are multiple and well identified. First of all, they are due to shocks to agricultural and food production at international level and to the logistics of distribution chains: war in Ukraine, disruption of logistics chains linked to the Covid-19 pandemic and geopolitical tensions, impacts of meteorological disasters linked to global warming such as the floods in Pakistan. Secondly, growing food demand in certain countries, notably China, is structurally destabilizing agri-food markets, partly as a result of the Chinese government's policy of ensuring food security through stockpiling, without coordination with other countries [4]. What could be the consequences of these brutal price hikes on the choices of French consumers, particularly the most disadvantaged?Les prix alimentaires augmentent de manière importante depuis maintenant plus d’une année. Les résultats provisoires publiés par l’Insee en janvier 2023 montrent une hausse de 13,2 % depuis janvier 2022, plus du double de la hausse de l’indice des prix (+6 %) et un peu moins que le prix de l’énergie (+16 %) [1]. Les données détaillées publiées par l’institut IRI montrent que les hausses de prix touchent particulièrement les aliments de base et les produits dits de « fond de placard », comme les huiles, le riz, le sucre ou les steaks hachés [2]. Les prix des produits « premiers prix » et de marques de distributeurs augmentent plus fortement que celui des marques nationales (+17,8 % pour les premier set +11,6 % pour les secondes [3]), probablement à cause de marges plus faibles qui obligent à transmettre plus directement la hausse des coûts des approvisionnements sur le prix final. Les déterminants de ces hausses de prix sont multiples et bien identifiés. Ils tiennent, tout d’abord, à des chocs sur la production agricole et alimentaire au niveau international et sur la logistique des chaînes de distribution : guerre en Ukraine, disruption des chaînes logistiques liées à la pandémie du Covid-19 et aux tensions géopolitiques, impacts de catastrophes météorologiques liées au réchauffement climatique comme les inondations au Pakistan. Ensuite, la croissance de la demande alimentaire de certains pays, notamment la Chine, déstabilise structurellement les marchés agro-alimentaires, en partie du fait de la politique du gouvernement chinois qui vise à assurer la sécurité alimentaire par la constitution de stocks et sans coordination avec les autres pays [4]. Quelles peuvent être les conséquences de ces hausses de prix brutales sur les choix des consommateurs franc¸ais, notamment les plus défavorisés
How Effective are Female Role Models in Steering Girls towards STEM? Evidence from French High Schools
No full textWe show in a large-scale field experiment that a brief exposure to female role models working in scientific fields affects high school students’ perceptions and choices of undergraduate major. The classroom interventions reduced the prevalence of stereotypical views on jobs in science and gender differences in abilities. They also made high-achieving girls in grade 12 more likely to enrol in selective and male-dominated science, technology, engineering and mathematics programs in college. Comparing treatment effects across the 56 role model participants, we find that the most effective interventions are those that improved students’ perceptions of science, technology, engineering and mathematics careers without overemphasising women’s under-representation in science
Régénération des forêts au Népal : le rôle moteur de la gestion participative
No full textInternational audienceLes groupements d’usagers de la forêt ont contribué à la restauration des forêts au Népal.Les groupements densifient les forêts et en augmentent légèrement la surface.En plus de mieux gérer la forêt, ils modifient les choix énergétiques des ménages
TBTs, firm organization and labor structure
No full textInternational audienceThis article investigates the effect of shocks to the occupational structure of exporting firms induced by the introduction of technical barriers to trade (TBTs) in importing countries. We rely on specific trade concerns data to identify trade‐restrictive TBT measures, combined with matched employer‐employee data for French exporters over the period 1995–2010, and information on the product‐destinations served by each exporter. Controlling for time‐invariant firm/occupation fixed effects and for time‐varying sector/occupation shocks, the 2SLS estimates show that exporting firms adapt to the imposition of TBTs at destination by increasing the share of managers at the expense of blue collars, white collars and other professionals
Anticipating the Risk of Dependency and Assets
No full textInternational audienceThe significant gains in life expectancy at advanced ages that have been recorded over recent decades, combined with the arrival of the baby boom generations at old age, suggest a rapid growth in the costs of long-term care. This perspective fuels debates on the most suitable method for financing the loss of autonomy: in the absence of sufficiently broad insurance coverage and given the difficulty of evaluating both the probability of becoming dependent and the attendant costs, the risk is high that households will not save enough. This article addresses the issue: by drawing on data from the 2020 wave of the Pat€r survey, we evaluate to what extent households adapt their savings effort in function of their estimation of the probability that they will lose their autonomy on the medical level. To this end, we estimate household assets according to their own assessment of the risk of becoming dependent one day, controlling notably for their self-reported health status. To account for the possible endogeneity of expected dependency risk on household savings (people save less if their health is poor), we use instrumental variable estimation methods. Our results confirm that people with a higher self-assessment of the risk of becoming dependent accumulate more assets: measured at the average self-assessed risk, an increase of this risk by one standard deviation is associated with an increase in overall gross wealth of three to eight months of permanent income
Macroeconomic Dynamics with Rigid Wage Contracts
No full textInternational audienceWe adapt the wage contracting structure in Chari (1983) to a dynamic, balanced-growth setting with recontracting as in Calvo (1983). The resulting wage-rigidity framework dampens income effects in the short run, thus allowing significant responses of hours to aggregate shocks. In reduced form, the model dynamics are similar to that in Jaimovich and Rebelo (2009), with their habit parameter replaced by our probability of wage-contract resetting. That is, if wage contracts are reset frequently, labor supply behaves in accordance with King, Plosser, and Rebelo (1988) preferences, whereas if they are never reset, we obtain the setting in Greenwood, Hercowitz, and Huffman (1988)