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Reinforcement generates systematic differences without heterogeneity
No full textInequality in outcomes may emerge through a reinforcement process in which stochastic variation in values is determined by prior values but may also originate in preexisting differences in unobserved factors. A common approach toward differentiating between these origins in longitudinal data is to attribute systematic differences between units—differences in means or differences proportional to a time-varying group average—to unobserved heterogeneity. We show that any longitudinal data with systematic differences can also be produced by a reinforcement-driven data generating process. This result reconciles findings in three distinct research areas—science of science, personal culture, and sexual networks—where reinforcement is a strong theoretical prior, yet longitudinal data analyses advance an explanation of interpersonal differences based on heterogeneity. Future studies may bound the role of heterogeneity and reinforcement from below by measuring fixed traits that systematically vary with the outcome and isolating random events that trigger emergent differences
Robustness of two-way fixed effects estimators to heterogeneous treatment effects
Get PDFThis paper studies the Two-Way Fixed Effects (TWFE) estimator in a general setting where multiple groups can enter and exit a binary treatment over time. It establishes necessary and sufficient conditions for this estimator to correspond to a convex combination of Average Treatment Effects (ATEs). I show that the TWFE estimator is a weighted sum of five different types of two-by-two comparisons, with positive weights. Parallel trends assumptions on either the untreated or treated potential outcomes must hold for each comparison to identify the ATE of the group switching treatment status. When treatment effects are contemporaneous but can be heterogeneous across groups and over time, both parallel trends assumptions are thus necessary and sufficient for the TWFE estimator to be a weighted sum of ATEs, with positive weights. Under parallel trends on the untreated potential outcomes and on the first exposure to treatment, the presence of dynamic treatment effects is necessary — but not sufficient — for this result to break
Negative results in science: blessing or (winner’s) curse
Get PDFTwo players receiving independent signals on a risky project with common value compete to be the rst to innovate. We characterize the equilibrium of this preemption game as the publicity of signals varies. Private signals create a winner's curse:investing rst implies that the rival has abstained from investing, possibly because he has privately received adverse information about the project. Since players want to gather more evidence in support of the project as a compensation, they invest later when signals are more likely to be private. Because of preemption, the NPV of investment is zero at equilibrium regardless of the publicity of signals. However, for a conservative planner who cares about avoiding unprotable investments, this implies that investment arises too early at equilibrium, and such a planner then prefers signals to be private. This provides a rationale against the mandatory disclosure of negative results in science, notably when competition is severe. Our results suggest that policy interventions should primarily tackle winner-takes-all competition, and regulate
transparency only once competition is suciently mild
Mixed Markov-Perfect Equilibria in the Continuous-Time War of Attrition
Get PDFWe prove the existence of a Markov-perfect equilibrium in randomized stopping times for a model of the war of attrition in which the underlying state variable follows a homogenous linear diffusion. We first prove that the space of Markovian randomized stopping times can be topologized as a compact absolute retract. This in turn enables us to use a powerful fixed-point theorem by Eilenberg and Montgomery [22] to prove our existence theorem. We illustrate our results with an example of a war of attrition that admits a mixed-strategy Markov-perfect equilibrium but no pure-strategy Markovperfect
equilibrium
Ethnic media and the mobilization of identity
No full textThis paper studies the relationship between ethnic media, which produce content in a minority language, and the success of ethnic parties. I argue that, by embedding cultural traits in entertainment products, media outlets can shape the salience of group identity, which helps parties’ mobilization efforts. I test this argument in the case of the Basque Country where, in the late phase of the Franco regime, an independent radio station operated by local clergy promoted the revival of regional language. Using contemporary, archival, and survey data, I show that exposure to ethnic radio increased support for new radical independentist parties and that the effect is driven by formerly Spanish-speaking municipalities with low historical support for Basque nationalism. I also show that radio increased bilingualism in subsequent generations and contributed to the bundling of ethnic identity revival and radical political ideology during the democratic transition
Contracts in the reform of the EU electricity market
No full textThis Policy Insight discusses the challenges facing the organisation of the electricity market through the lens of the EU’s market reform. Two goals that the electricity market should consider are discussed: first, ensuring the optimal dispatching of existing electricity generation at the lowest cost, and second, fostering efficient and reliable investment in new generation to reach the EU’s decarbonisation targets. The authors then investigate the challenges associated with developing long-term contracts for electricity generation
Universités et capitalisme académique : liberté académique, responsabilité sociale et dynamiques inconscientes
No full textCet article examine comment le capitalisme académique pousse les universités à se comporter comme des acteurs du marché, mettant en péril leur indépendance et leur liberté académique. En abordant les mécanismes inconscients liés au désir et au narcissisme, il montre l’impact des exigences de performance sur les enseignants et les étudiants. L’auteur plaide en faveur de la défense de la liberté académique pour préserver la diversité des idées et assurer le bien-être dans l’enseignement supérieur. Il propose aussi des pistes pour trouver un équilibre entre responsabilité sociale et contraintes économiques. Une lecture incontournable pour saisir les enjeux actuels des universités
