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From geometric quantiles to halfspace depths: A geometric approach for extremal behaviour
No full textWe investigate the asymptotics for two geometric measures, geometric quantiles and halfspace depths. While much literature is known on the population side, we fill out some gaps there to obtain a full picture, before turning to the sample versions, where the questions on asymptotics become crucial in view of applications. This is the core of the paper: We provide rates of convergence for the sample versions and address the extremal behaviour of the geometric measures according to the type of underlying distribution
Effective Tax Rates and Firm Size
No full textThis paper provides novel evidence on the relationship between firm size and effective corporate tax rates using full-population administrative tax data from 13 countries. In all countries, small firms face lower effective tax rates than mid-sized firms due to reduced statutory tax rates and a higher propensity to register losses. In most countries, effective tax rates fall for the largest firms due to the take-up of tax incentives. As a result, a third of the top 1 percent of firms face effective tax rates below the global minimum tax of 15 percent. The minimum tax could raise corporate tax revenue by 27 percent in the median sample country
Media Mergers in nested Markets
No full textNational audienceWe analyze the effect of media mergers in a model that stresses, on the one hand, the fact that media are two-sided platforms willing to attract advertisers and viewers and, on the other hand, that strong competitors have emerged to challenge traditional media on both sides. We show that a merger has two conflicting effects on traditional media’s incentives to invest in quality programs and to exploit their market power. When competition is primarily between traditional media, a Business-Stealing Effect dominates, and the merger is detrimental to advertisers and viewers. When the competition is mainly between the traditional media and their new competitors, an Ecosystem Effect dominates, and the merger benefits advertisers and viewers. We extend this setting to discuss the role of financial constraints that might limit investments in the quality of programs and show that the same effects are at play
The Energy efficiency gap in the rental housing market: it takes both sides to build a bridge
No full textInternational audienc
Riding Together: Eliciting Travelers' Preferences for Long-Distance Carpooling
No full textMost seats in private cars are empty when drivers hit the road. Carpooling could thus represent a low-cost strategy to reduce carbon emissions in the transportation sector. Using revealed preference data from actual long-distance carpooling trips in France, we estimate passengers' preferences for the different characteristics of a ride. We find that passengers are highly price-elastic and value significantly the convenience of pick-up and drop-off locations. In contrast, their value of time once in the car is significantly lower than typical reference values. Finally, we discuss the effectiveness of a number of counterfactual policies aimed at promoting carpooling
Change point detection in low-rank VAR processes
No full textVector autoregressive (VAR) models are widely used in multivariate time series analysis for describing the short-time dynamics of the data. The reduced-rank VAR models are of particular interest when dealing with high-dimensional and highly correlated time series. Many results for these models are based on the stationarity assumption that does not hold in several applications when the data exhibits structural breaks. We consider a low-rank piecewise stationary VAR model with possible changes in the transition matrix of the observed process. We develop a new test of presence of a change-point in the transition matrix and show its minimax optimality with respect to the dimension and the sample size. Our two-step change-point detection strategy is based on the construction of estimators for the transition matrices and using them in a penalized version of the likelihood ratio test statistic. The effectiveness of the proposed procedure is illustrated on synthetic data
Knowledge contributions in design science research: Paths of knowledge types
No full textInternational audienc
A 'placental system' to coordinate large firms and startups within corporate innovation boundary structures
No full textInternational audienc
We modeled long memory with just one lag!
No full textInternational audienceTwo recent contributions have found conditions for large dimensional networks or systems to generate long memory in their individual components. We build on these and provide a multivariate methodology for modeling and forecasting series displaying long range dependence. We model long memory properties within a vector autoregressive system of order 1 and consider Bayesian estimation or ridge regression. For these, we derive a theory-driven parametric setting that informs a prior distribution or a shrinkage target. Our proposal significantly outperforms univariate time series long-memory models when forecasting a daily volatility measure for 250 U.S. company stocks over twelve years. This provides an empirical validation of the theoretical results showing long memory can be sourced to marginalization within a large dimensional system
Managing Cyber Risk, a Science in the Making
No full textNot a day goes by without news about a cyber attack. Fear spreads out and lots of wrong ideas circulate. This survey aims at showing how all these uncertainties about cyber can be transformed into manageable risk. After reviewing the main characteristics of cyber risk, we consider the three layers of cyber space: hardware, software and psycho-cognitive layer. We ask ourselves how is this risk different from others, how modelling has been tackled and needs to evolve, and what are the multi-facetted aspects of cyber risk management. This wide exploration pictures a science in the making and points out the questions to be solved for building a resilient society