Publications

Résumé Objective. Eyewitness testimony strongly influences conviction and sentencing; yet false testimony is a leading cause of wrongful convictions. We investigate whether the truth-telling oath — common in legal systems — reduces eyewitness deception. Hypothesis. While prior work emphasizes eyewitness reliability, little is known about whether courtroom procedures like the oath increase truthfulness. Drawing on psychological and economics literature, we hypothesize that oath-taking acts as a commitment device that reduces deception. Method. In a 22 between-subjects experiment combining legal psychology and experimental economics, participants watched a video and answered questions under varying incentive and oath conditions. Performance-based incentives conflicted with honesty, allowing us to isolate the effect of the oath. Results. The oath reduced deception by 39.2% (95% CI [20.1, 59.5]) even under incentives to lie, without impairing truth-tellers’ performance. Conclusions. The courtroom oath is not merely symbolic — it plays a measurable and substantial role in enhancing the integrity of eyewitness testimony. Eyewitness testimony is the most powerful form of evidence in a court of law. Eyewitnesses affect both the odds of conviction and the severity of sentences of the guilty. But eyewitnesses also lie, and false testimony is the primarily cause of wrongful convictions. Most of the extant literature focuses on eyewitness reliability and credibility assessment, but very little is known about the efficiency of the main mechanism used in-field to foster eyewitness honesty: a solemn truth-telling oath—the most ancient and worldwide institution used in the solemn legal ceremony underpinning criminal cases. Herein we examine how the truth-telling oath actually affects the level of eyewitness deception. Using a controlled experimental test designed to address this question, we show that an eyewitness who is exogenously incentivized to lie and takes a solemn oath is significantly less likely to use deception. In contrast with the related literature focusing on the detection of lies, we show that an oath actually works to improve truth-telling. The oath is not just ceremonial, it plays a key role in improving efficiency within the court.
Mots clés Eye-witness testimony, Truth-telling oath, Controlled experiment
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Résumé The modernisation theory of regime change is often perceived to be a murky paradigm, lacking theoretical or empirical foundations. In response, we clarify the links between education and regime change.More specifically, we propose that education contributes indirectly to the collapse of autocratic regimes because educated people engage in non-violent (civil) resistance that reduces the effectiveness of the security apparatus. We empirically test the validity of this 'defanging effect' of education. We indeed find that the combination of high autocracy and high education levels tends to trigger non-violent campaigns, which in turn increases the likelihood of a regime change, likely to be associated with political liberalisation.
Mots clés Regime change, Modernisation, Education, Democratisation, Civil resistance, Autocracy
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Résumé Preventive behaviors are crucial for controlling the spread of infectious diseases. Until now, most of the literature on the understanding of the willingness to comply with preventive behaviors at the individual level has focused on either one of those behaviors or studied several behaviors but independently. However, preventive behaviors might not be independent of each other, and the question of the relationship between these various behaviors deserves to be further investigated. The COVID-19 pandemic represents an interesting setting to study compliance with preventive behaviors when several prophylactic measures aiming to reduce the same infection risk are available. The aim of this study is to investigate how economic and social preferences may shape the relationship between three types of COVID-19 preventive behaviors among a representative sample of the French population: 1) compliance with restrictions on movement, 2) adherence to barrier gestures and 3) COVID-19 testing. Using a Latent Class Analysis, we identify four groups of individuals with diverging patterns of compliance with preventive behaviors, differing both in terms of intensity and types of prophylactic measures followed: individuals who apply all preventive behaviors, those who reject them all, individuals who do not respect restrictions on movement but still protect themselves and others by applying barrier gestures, and those who do not use barrier gestures but comply with restrictions on movement. Our results support the existence of a risk compensation process leading some individuals to tailor their menu of preventive behaviors until they reach the risk threshold they are willing to handle. The composition of the menu of preventive behaviors appears to be linked with individuals' economic and social preferences including risk and time preferences, prosociality, and interpersonal trust. Exploring heterogeneity in preventive behaviors may inform the design of targeted prevention and communication campaigns that are better tailored to achieve public health goals.
Mots clés Infectious diseases, Economic and social preferences, Latent class analysis, Risk compensation, Preventive behaviors
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Résumé SkyRank is an open source Python framework designed to implement, compare, and visualize various Skyline ranking algorithm implementations, including dp-idp improved with dominance hierarchy, RankSky, CoSky, and DeepSky. While these methods have been independently introduced in the literature, SkyRank provides a unified, reproducible, and extensible platform to evaluate and visualize them interactively. SkyRank is designed for researchers, students, and practitioners working on multi-criteria decision making, Pareto dominance, and database preference queries. It includes a modular benchmarking backend, a LaTeX-compatible graph generator, and two graphical user interfaces (based on PyQt5 and Tkinter) for interactive data exploration.
Mots clés Ranking, Open source, Algorithm, Dp-idp, RankSky, CoSky, DeepSky, Skyline
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Résumé SkyRank is an open source Python framework designed to implement, compare, and visualize various Skyline ranking algorithm implementations, including dp-idp improved with dominance hierarchy, RankSky, CoSky, and DeepSky. While these methods have been independently introduced in the literature, SkyRank provides a unified, reproducible, and extensible platform to evaluate and visualize them interactively. SkyRank is designed for researchers, students, and practitioners working on multi-criteria decision making, Pareto dominance, and database preference queries. It includes a modular benchmarking backend, a LaTeX-compatible graph generator, and two graphical user interfaces (based on PyQt5 and Tkinter) for interactive data exploration.
Mots clés Ranking, Open source, Algorithm, Dp-idp, RankSky, CoSky, DeepSky, Skyline
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Résumé Honest and dishonest behaviors may both diffuse among the members of an organization. Knowing which of the two spreads faster is important because it impacts the extent to which managers will need to resort to other, potentially more costly solutions to curb dishonest behavior. Assessing empirically which of honest behavior or dishonest behavior spreads faster is challenging because this requires field measurements of social relationships and dishonest behavior of individual members, which poses both measurement and inference problems. We examine an original fine-grained data set from a large company that allows for identifying agents likely to be dishonest and interactions among employees while offering a natural experiment that circumvents the inference problems associated with identifying peer-to-peer diffusion. We find (1) that dishonest behavior diffuses, whereas honest behavior does not; (2) that diffusion likely operates through spreading information about opportunities for collusion; and (3) that policies that screen on dishonesty at hiring may be efficient to curb dishonest behavior in environments with high turnover. This paper was accepted by Lamar Pierce, organizations. Funding: R. Ferrali acknowledges support from the Mamdouha S. Bobst Center for Peace and Justice [Grant 2016-12-Bobst], the French National Research Agency [Grant ANR-17-EURE-0020], and Aix-Marseille University—A*MIDEX [Excellence Initiative]. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2023.01981 .
Mots clés Dishonesty, Natural experiment, Organization Behavior, Network analysis
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Résumé Background It is commonly believed that Africa largely evaded the worst of the COVID-19 pandemic, with fewer cases than other continents. However, regional comparisons that ignore differences in testing intensity may misrepresent dynamics. Studying the spread and case-fatality relationship during COVID-19 across WHO regions requires explicitly adjusting for time-varying test volumes. Methods We build a weekly panel dataset spanning May 2020 to December 2021 for the WHO regions: Africa, Eastern Mediterranean, South-East Asia, the Americas, Western Pacific, and Europe. Data on tests, confirmed cases, and COVID-19-attributed deaths were sourced from Our World in Data. We apply a novel metric that corrects for fluctuating test volumes to quantify week-to-week acceleration in infections and in mortality. We then compare the frequency, magnitude, and timing of these acceleration episodes across regions.Results Accounting for testing dynamics, we show that Africa exhibits multiple infectionacceleration episodes whose magnitude and frequency match those in other regions. Mortality accelerations in Africa closely follow infection surges, with an average lag of ten weeks. A positive correlation between infection acceleration in Africa and the Americas further indicates synchrony. These findings hold when using a larger secondary dataset of 140 countries. Conclusions Contrary to prevailing assumptions, Africa was not spared from the pandemic's severe dynamics. Infection surges were on par with those elsewhere and were followed by mortality accelerations. These results underscore that accounting for testing variability is essential to accurately assess pandemic progression, and they highlight the urgent need to strengthen surveillance and healthcare capacity across all regions.The relatively low number of reported COVID-19 cases and deaths in Africa has prompted debates about whether the continent was spared the worst of the pandemic, a phenomenon described by some as the African "puzzle" 1,2 or "paradox" 3 . Early media reports and research articles speculated that Africa's younger population, lower population density in rural areas, and prior experience with infectious diseases and their pharmaceutical treatments might have mitigated the severe impacts observed in other regions.However, emerging evidence from seroprevalence studies indicates that far more individuals in Africa were exposed to SARS-CoV-2 than is reflected in official surveillance data, especially during the pandemic's first 2 years. For example, the ratio of seroprevalence to confirmed cases has been estimated to be as high as 100:1 4 . This gap between seroprevalence estimates and reported cases grew as the pandemic continued 5 , suggesting substantial under-reporting in surveillance data. For example, while 6 mention low testing rates as a likely source of under-reporting in their discussion of the
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Résumé This study provides a life-course analysis of the relationship between self-employment, health, and health care use among individuals aged 50 and older in Europe. Using data from the Survey of Health, Ageing, and Retirement in Europe (SHARE), we apply first-difference and dynamic panel data models that go beyond standard approaches in mitigating endogeneity concerns. Our findings show that the self-employed enjoy better health at younger ages, consistent with a selection effect. In addition, they experience a steeper decline in physical health over time. We also document two distinct phases of health care use: during working life, the self-employed are more likely to be hospitalised, suggesting delayed care until acute needs arise; after retirement, the number of medical visits increases, consistent with a lower opportunity cost of care.
Mots clés Self-employment, SHARE, Health care use, Health
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Résumé We study candidates' position adjustments in response to information about voters' preferences. Repositioning allows candidates to move closer to the median voter, but it incurs financial and electoral costs. In a subgame-perfect equilibrium, candidates diverge from the center ex ante if the costs of adjustment are sufficiently large. This allows them to increase the chances of a costless victory when the information is strongly in their favor. Our theory highlights a dynamic of moderation during the campaign stage in competitive elections, as well as a prominent role for minor adjustments made preemptively by the favored candidate. JEL Classification: C72, D72, D82 Model. We enrich the Downs-Hotelling framework by introducing an information shock, creating a two-stage game. The shock reveals the location of the median voter. This captures the idea that voters' aggregate preferences fluctuate over time and that their current leanings are disclosed during the electoral cam-This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Mots clés Re-positioning, Spatial voting, Imperfect information, Flip-flop
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Résumé Background: Breast cancer and its treatment may contribute to an increased risk of unemployment, influenced by both disease-related factors and socioeconomic determinant. Few longitudinal studies have examined employment outcomes among women diagnosed with cancer. This retrospective study investigated long-term employment among breast cancer survivors (BCS) and assessed disease specific and socioeconomic factors associated with employment. Design and methods: Registry-based data included working age BCS in Norway 2004–2008 alive at 6 years follow-up ( N = 3560). The employment status on each BCS was compared to two matched non-cancer controls ( N = 7081) by means of logistic regression analyses with marginal effects. Separate analyses by employment status at the time of diagnosis were conducted. Results: Among BCS employed at diagnosis, 73.7%, 71.5% and 71.8% of BCS were in employment at 1, 2 and 6 years after diagnosis, respectively. BCS employed at diagnosis had significantly lower probability of being employed at all follow-up time points, compared to controls. BCS outside employment at the time of diagnosis experienced lower probability of employment compared to controls. BCS with secondary or higher education had higher probability of employment compared to BCS with basic education, and BCS living in families with children were more likely to enter employment during follow-up compared to BCS without children. Conclusions: BCS employed at diagnosis had a subsequent risk of unemployment, and BCS not employed at diagnosis had lower probability of entering employment. Additional risk factors are high age, low education, and being single without children. Significance for public health: The risk of unemployment after a breast cancer diagnosis was increased. Job loss is costly economically and socially, both for individuals and for society. Early focus on employment particularly among employees with low education and with little family support may alleviate this problem.
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Résumé Climate change is a global phenomenon that has a significant impact on commodity prices. This paper analyzes the impact of El Niño–Southern Oscillation (ENSO) on global commodity prices, using a Global Factor Local Projections (GFALP) model. Firstly, we demonstrate that unanticipated ENSO movements contribute to commodity price volatility asymmetrically during El Niño and La Niña periods. Secondly, climate change might disrupt ENSO patterns. We compare the current situation with potential climate change outcomes to evaluate its impact on commodity price stability. We compute an index measuring commodity price exposure to these disruptions. We demonstrate that in most cases, these shifts exacerbate commodity price volatility. Finally, we explore several avenues to explain the observed heterogeneity in the exposure of commodity prices to the evolution of ENSO that could result from climate change, and we highlight the crucial role of international commodity markets in adapting to climate change.
Mots clés Climate change, Agriculture, Energy, Commodity Price, ENSO
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Résumé We test for cheap talk between husbands and wives in farm households. In a labin-the-field experiment, husbands allocate inputs between their own plot and their wife's higher-return plot. We vary how returns on the wife's plot are communicated. Across all treatments, husbands underinvest in their wife's land. We model this with limited enforcement of marital agreements and derive additional predictions. Allocative inefficiencies are greater when women hold private information, especially in households with low resource sharing under full information. Communication only partly offsets inefficiencies, and only when information is verifiable ex post.
Mots clés Household behavior, Lab-in-the-field experiment, Cheap talk, Asymmetric information
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Résumé This paper studies the main determinants of bilateral financial flows in the euro area to achieve sustainable and fair financing opportunities. We revisit the modern theory of the optimal currency area considering the impact of heterogeneity in inequality measures, within and across countries, on cross border financial flows. To do so, we introduce financial and social fragmentation in gravity models of European capital flows. We use data from 19 Eurozone countries from 2000 to 2021 and show how fragmentation impacts capital flows, namely foreign direct investment, cross-border loans as well as portfolios, equity and bond flows. Since capital is, in principle, free to flow in the Eurozone, our analysis directly identifies the roles of potential sources of fragmentation: social inequalities, lack of market openness, and domestic regulations such as macroprudential controls. Overall, our results show that financial integration in Europe entails more capital flows of any type while social fragmentation across European countries is detrimental to capital flows, no matter which type. This is strong evidence of the importance of financial and social fragmentation in the Eurozone on the distribution of capital.
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Résumé While men and women make joint decisions about fertility, women give birth and are more likely to learn about a significant cost of childbearing-maternal health risk. Within couples in Zambia, men have systematically lower awareness of maternal risk factors and a higher desire for children than their wives. We develop a model in which information asymmetries between partners regarding maternal health risk can persist in equilibrium as the result of strategic incentives and can generate disagreement over fertility that cannot be resolved with transfers. To study the effect of communication barriers on fertility, we design an experiment that varies whether the husband or the wife receives information about maternal health risk. One year after the intervention, directly treated men exhibit significant gains in knowledge, report lower demand for children, and communicate this information to their wives, who also update their beliefs. Pregnancy falls significantly, while transfers remain unchanged relative to the control group. Meanwhile, when women are treated directly, they update their own beliefs, but fail to transmit the information to their husband, who do not change their demand for children. While pregnancy also falls among these couples, the decline is accompanied by a significant reduction in transfers and support from husband to the wife. When childbearing costs, particularly those borne by one party, cannot be easily communicated within the household, targeting information can help overcome asymmetries and improve household decision-making.
Mots clés Household decision-making, Fertility, Communication
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Résumé Drift and volatility are two mainsprings of asset price dynamics. While volatilities have been studied extensively in the literature, drifts are commonly believed to be impossible to estimate and largely ignored in the literature. This paper shows how to detect drift using realized autocovariance implemented on high-frequency data. We use a theoretical treatment in which the classical model for the efficient price, an Itō semimartingale possibly contaminated by microstructure noise, is enriched with drift and volatility explosions. Our theory advocates a novel decomposition for realized variance into a drift and a volatility component, which leads to significant improvements in volatility forecasting.
Mots clés Volatility Forecasting, Serial Covariance, High-frequency Data, Drift
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Résumé Not all barrels of oil are created equal: their extraction varies in both private cost and carbon intensity. Leveraging a comprehensive micro-dataset on world oil fields, alongside detailed estimates of carbon intensities and private extraction costs, this study quantifies the additional emissions and costs from having extracted the “wrong” deposits. We do so by comparing historical deposit-level supplies to counterfactuals that factor in pollution costs, while keeping annual global consumption unchanged. Between 1992 and 2018, carbon misallocation amounted to at least 11.00 gigatons of CO2-equivalent (GtCO2eq), incurring an environmental cost evaluated at $2.2 trillion (US$ 2018). This translates into a significant supply-side ecological debt for major producers of high-carbon oil. Looking forward, we estimate the gains from making deposit-level extraction socially optimal at about 9.30 GtCO2eq, valued at $1.9 trillion, along a future aggregate demand pathway coherent with the objective of net-zero emissions in 2050, and document unequal reserve stranding across oil nations.
Mots clés Misallocation, Stranded assets, Carbon mitigation, Oil
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