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Applying the Dempster–Shafer Fusion Theory to Combine Independent Land-Use Maps: A Case Study on the Mapping of Oil Palm Plantations in Sumatra, Indonesia
No full textAll data and codes used are available on a GitHub directory: https://github.com/CarlBethuel/Dempster-Shafer-work.International audienceThe remote sensing community benefits from new sensors and easier access to Earth Observation data to frequently released new land-cover maps. The propagation of such independent and heterogeneous products offers promising perspectives for various scientific domains and for the implementation and monitoring of land-use policies. Yet, it may also confuse the end-users when it comes to identifying the most appropriate product to address their requirements. Data fusion methods can help to combine competing and/or complementary maps in order to capitalize on their strengths while overcoming their limitations. We assessed the potential of the Dempster-Shafer Theory (DST) to enhance oil palm mapping in Sumatra (Indonesia) by combining four land-cover maps, hereafter named DESCALS, IIASA, XU, and MAPBIOMAS, according to the first author's name or the research group that published it. The application of DST relied on four steps: (1) a discernment framework, (2) the assignment of mass functions, (3) the DST fusion rule, and (4) the DST decision rule. Our results showed that the DST decision map achieved significantly higher accuracy (Kappa = 0.78) than the most accurate input product (Kappa = 0.724). The best result was reached by considering the probabilities of pixels to belong to the OP class associated with DESCALS map. In addition, the belief (i.e., confidence) and conflict (i.e., uncertainty) maps produced by DST evidenced that industrial plantations were detected with higher confidence than smallholder plantations. Consequently, Kappa values computed locally were lower in areas dominated by smallholder plantations. Combining land-use products with DST contributes to producing state-of-the-art maps and continuous information for enhanced land-cover analysis
A dynamic analysis of criminal networks
No full textInternational audienceWe take a novel approach based on differential games to the study of criminal networks. We extend the static crime network game (Ballester et al., 2006, 2010) to a dynamic setting where criminal activities negatively impact the accumulation of total wealth in the economy. We derive a Markov Feedback Equilibrium and show that, unlike in the static crime network game, the vector of equilibrium crime rates is not necessarily proportional to the vector of Bonacich centralities. Next, we conduct a comparative dynamic analysis with respect to the network size, the network density, and the marginal expected punishment, finding results in contrast with those arising in the static crime network game. We also shed light on a novel issue in the network theory literature, i.e., the existence of a voracity effect. Finally, we study the problem of identifying the optimal target in the population of criminals when the planner’s objective is to minimize aggregate crime at each point in time. Our analysis shows that the key player in the dynamic and the static setting may differ, and that the key player in the dynamic setting may change over time
L'effet des compétences scolaires sur les salaires futurs
No full textCe Focus propose une estimation de l'effet d'une amélioration des compétences scolaires sur les salaires futurs en France. Les politiques éducatives sont essentielles pour renforcer les compétences des élèves et optimiser la performance du système éducatif, contribuant ainsi à la formation du capital humain des générations à venir. En France, l'éducation représente le deuxième poste de dépenses publiques, ce qui renforce la nécessité d'en évaluer précisément l'efficacité. Parmi ces nombreux bénéfices, l'impact sur les revenus futurs des individus est particulièrement déterminant, en raison du lien étroit entre compétences scolaires et insertion professionnelle. Cependant, mesurer cet effet reste complexe, notamment en raison du délai entre la mise en place des politiques éducatives et leurs répercussions sur les trajectoires professionnelles. En exploitant les résultats des évaluations nationales des élèves de 6e de 1995, nous analysons leur influence sur les revenus d'entrée dans la vie active à l'aide de l'équation de Mincer. Cette estimation, peu documentée en France, est pourtant essentielle pour orienter les investissements publics dans l'éducation. Son estimation contribue à calibrer l'indicateur d'efficacité des dépenses publiques (EDP), permettant ainsi d'évaluer l'impact des politiques éducatives sur les revenus futurs des bénéficiaires. Nos résultats montrent qu'une amélioration d'un écart-type des compétences scolaires est associée à une hausse d'environ 10% des salaires futurs, soit un ordre de grandeur comparable à celui observé dans les études internationales. Bien que cette approche présente certaines limites méthodologiques, liées notamment au suivi restreint des trajectoires salariales, elle fournit une première estimation du rendement économique de l'éducation en France
Distance entre métiers et transitions professionnelles des demandeurs d’emploi après une formation
No full textInternational audienceDoes vocational training help correct structural imbalances in the labour market? We propose a new measure of the skills distance between occupations, obtained by fine-tuning a large language model on a sample of job offers. Using this method, we demonstrate that the "return to employment" differential between jobseekers with and without training is driven by a reallocation of workers towards occupations that are very different from their previous posts in terms of the skills required. From a purely reallocative perspective, however, the return to employment differential associated with vocational training does not appear to be driven by more jobseekers moving to occupations where employers are struggling to recruit.La formation professionnelle contribue-t-elle à la résorption des déséquilibres structurels du marché du travail ? Nous construisons une nouvelle mesure d'écart de compétences entre métiers grâce à l'application d'un algorithme de traitement du langage à un échantillon d'offres d'emploi. En utilisant cette mesure, nous montrons que le différentiel de retour à l'emploi entre demandeurs d'emploi formés et non formés est tiré par les réallocations vers des métiers éloignés en termes de compétences par rapport à celui du dernier poste occupé. D'un point de vue purement réallocatif, le différentiel de retour à l'emploi lié à la formation professionnelle ne semble cependant pas être tiré par des redirections plus nombreuses vers des métiers en forte tension
Essais sur les inégalités sociales de santé
No full textSocial health inequalities emerge as early as pregnancy and childhood and persist throughout life: a more favorable socioeconomic situation leads to a longer and healthier life. In my research, I have focused on measuring (social) health inequalities using an axiomatic approach. I have also explored the relationship between socioeconomic status and health using econometric tools, in both France and the United Kingdom. Various population groups have drawn my attention -- for example, precarious workers, children and adolescents, adults, and older people. Some of my work is descriptive, measuring the association between socioeconomic status and health, while other studies aim to identify the causal effect of economic conditions on health. My research perspectives build on my previous work; they focus on students' diet and nutrition in the Île-de-France region, social health inequalities through the lens of gender in France, and the relationship between macroeconomic conditions and health status.Des inégalités sociales de santé apparaissent dès la grossesse et l’enfance et persistent tout au long de la vie : une situation socioéconomique plus favorable permet une vie plus longue et en meilleure santé. Dans mon travail de recherche, je me suis intéressée à la mesure des inégalités (sociales) de santé, dans une démarche axiomatique. J'ai aussi exploré le lien entre statut socioéconomique et santé, à l'aide d'outils économétriques, en France et au Royaume-Uni. Différents groupes de population ont retenu mon attention : par exemple, certains travailleurs et travailleuses précaires, les enfants et les adolescent(e)s, les adultes et les seniors. Certains de mes travaux sont descriptifs, mesurant l'association entre la situation socioéconomique et l'état de santé, alors que d'autres cherchent à identifier l'effet causal des conditions économiques sur la santé. Mes perspectives de recherche s'inscrivent dans la continuité de ce travail ; elles portent sur l'alimentation des étudiant(e)s en Île-de-France, les inégalités sociales de santé au prisme du genre en France, et le lien entre conditions macroéconomiques et état de santé
Resolutions in a system of financially linked firms: relying on coarse information
No full textInternational audienceIn a financial system, firms hold debts both within and outside the system. To limit miscoordination and cascades of defaults, an orderly resolution must be conducted at the system level and simultaneously liquidate all debts. This paper analyzes such resolutions under two main assumptions. First, a default on external creditors, say on banks' customers, triggers bankruptcy and should be avoided as much as possible because of large negative externalities. Second, resolutions are coarse, as they specify the payments between each firm and its external creditors and the system without specifying the reimbursement of each bilateral liability. I present properties that determine which firms become bankrupt and how much each non-bankrupt firm reimburses to and receives from the system. The main properties rely on the priority of external creditors at the system level, which reflects the policy recommendations after the 2018 financial crisis, and the proportionality principle
Sharing Model Uncertainty
No full textInternational audienceThis paper examines efficient allocations in economies where consumers exhibit heterogeneous smooth ambiguity preferences and face model uncertainty with a common set of identifiable models. Aggregate endowment is ambiguous. We characterize economies where the representative consumer is of the smooth ambiguity type and derive efficient sharing rules. Heterogeneous ambiguity aversion leads to sharing rules that systematically differ from those in vNM-economies. The representative consumer’s ambiguity aversion differs from that of the typical consumer; this leads to more compelling asset-pricing predictions. We focus on point-identified models but show that our insights extend to partially-identified models
Children Costs in a One-Adult Household: Empirical Evidence from the UK
No full textThis paper addresses two central questions in family and economic policy. First, to what extent are estimates of the cost of children derived from two-parent households applicable to single-parent families? Second, is the recently introduced two-child limit policy in the UK appropriate given the diversity of family structures? To address these questions, I propose a collective consumption model for one-adult households, apply it to three datasets-the Family Expenditure Survey, the Expenditures and Food Survey, and the Living Costs and Food Survey in the UK-and present two key findings. First, child cost estimates derived from two-parent households remain externally valid for single-parent families, at least for single mothers. Second, in low-income families, household size plays a crucial role in determining the proportion of resources allocated to children, a factor less relevant for higher-income families. This suggests that the two-child limit policy would likely exacerbate inequalities and increase child poverty within low-income families.</div
The Chair Allocation problem
No full textInternational audienceWe introduce the Chair Allocation problem, a three-sided matching market where researchers apply for a chair in a university, and universities request chairs (composed of a university and a research topic) to a central authority. We propose a new algorithm, the Chair Nested Deferred Acceptance algorithm, and show that it is fair, undominated by other fair assignments, and strategy-proof for researchers
Beyond the trees: Equity and justice in Nepal’s forest restoration
No full textInternational audienceWe examined equity and justice in forest restoration programs in Madhesh province in Nepal. We selected four sites that have three different tenure regimes, namely, community forest (Baghbhairav and Musahar), collaborative forest management (Tamagadhi), and forest protection area (Dhanushadham). The primary data were collected through focus group discussion, key informant interviews, field observations, and forest cover change analysis. We used ArcGIS to perform a spatial overlay analysis to identify the forest cover dynamic (1990, 2000, 2010, and 2022), followed by an examination of equity and justice under its four dimensions: contextual, procedural, distributive, and recognition. Atlas.ti, a computer-assisted software, was used to create codes, sub-themes, and themes from qualitative information, which were then used for further interpretations. Our findings indicated that while forest cover in the study sites is changing rapidly, with temporal and spatial variation across the sites, restoration and equity are inextricably linked and mutually reinforce each other. We also identified visible interactions among the four dimensions of equity, with each contributing to restoration in a different way. The paper concludes that multiple factors undermine forest restoration, among them, equity and justice,community heterogeneity, weak tenure rights, and conflicts over forest benefits sharing are the prominent. The findings imply that, for successful restoration, equity and justice must be considered as the core elements for both intrinsic and instrumental reasons