CHONE Philippe

Linear demand systems and quasi-linear quadratic utility models are widely used in industrial economics. We clarify the link between the two settings and explain their exact origin as it seems to be little known by practitioners. We offer practical recommendations to achieve consistency, tractability and a reasonable degree of generality when using the linear demand framework. We show that all tractable versions of the model used in practice are (almost) identical and have a mean-variance structure. We provide concise, ready-to-use formulae for the symmetric model. Finally, we revisit and extend the asymmetric model of Shubik and Levitan.

This thesis deals with the platform economy through three independent chapters. The first one develops a theoretical model around exclusive sales, or flash sales. This practice, which is very common on the Internet, consists in offering consumers a take-it-or-leave-it offer today, without the possibility of benefiting from it tomorrow. The second chapter evaluates the substitutability of the different distribution channels for hotel rooms in Scandinavia, in particular between the hotel's website, Booking, and Expedia. We also analyze the decision of a hotel chain to boycott a sales channel. Finally, the third chapter analyzes the implementation of a new strategy by Booking with its hoteliers, and tries to determine its different components.

This thesis is in the fields of public economics and political economy and is structured around two axes. The first and second chapters focus on redistributive policies. Specifically, they present contributions to income tax theory and adopt both a normative and a political perspective. The third and fourth chapters contribute to a better understanding of the political forces guiding reforms in multistate unions such as the European Union. They focus on the preferences of individuals who are of great importance in the decision-making process but about whom we have little direct information: politicians.My first and second chapters seek to enrich a standard model of optimal taxation, in order to better account for institutional and social contexts. Chapter 1 addresses the question of how to design a tax system when the ties between individuals are taken into account. Indeed, until now, income taxation theory has always focused on redistribution between separate individuals (or couples). But in many contexts, individuals are linked to their family, friends, village or community members, and make regular transfers to them. These transfers go from the richest to the poorest, and thus represent a form of informal redistribution. My research question is: How should the existence of these informal but redistributive transfers affect the design of taxation systems? Chapter 2 examines a salient feature of many developed countries: the large proportion of the population that does not pay income tax. Using tools from the normative tax literature that we apply to a political economy framework, we study the political economy of nonlinear tax reforms, which helps us understand why such a large share of the population is exempt from paying income tax in some countries. Although both chapters are theoretical, I use administrative and survey data to illustrate and draw concrete conclusions from my models.The last two chapters of my dissertation focus on the preferences of French and German parliamentarians on different European integration measures and are based on a first wave of questionnaire surveys conducted in 2016. In the future, we plan to continue these surveys on a regular basis in order to better understand the dynamics of the European Union and to provide an academic perspective to current EU debates with insights. The third and fourth Chapters thus explore MEPs' views on policies that, in light of the current debates and the past ten years, are of particular importance: labor market policies and European monetary union. They offer a new approach to questions of political economy by focusing on the views of a set of important actors in the decision-making process: politicians, for whom, apart from their public votes and statements, we have little direct information. In these chapters, we seek to disentangle which of the two factors is more important in the observed differences: cultural or ideological? Surprisingly, we find that for a majority of questions, the answers reflect an ideological rather than a Franco-German divide. For example, the creation of a common unemployment insurance and greater flexibility in the labor market point to a much more ideological than national divide. These results may help to highlight potential directions for European integration that could prove fruitful.

Linear demand systems and quasi-linear quadratic utility models are widely used in industrial economics. We clarify the link between the two settings and explain their exact origin as it seems to be little known by practitioners. We offer practical recommendations to achieve consistency, tractability and a reasonable degree of generality when using the linear demand framework. We show that all tractable versions of the model used in practice are (almost) identical and have a mean-variance structure. We provide concise, ready-to-use formulae for the symmetric model. Finally, we revisit and extend the asymmetric model of Shubik and Levitan.

The quasi-linear quadratic utility model is widely used in economics. The knowledge of its exact origin is less widespread. A first contribution of the paper is to explain the genesis of this model. Next, we review the main properties of the general model, mainly following the previous literature. Finally, it is shown that all the tractable versions of the model used in practice are (almost) identical and have a mean variance structure. We provide ready-to-use formulae for this symmetric model.

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The purpose of this doctoral thesis is to evaluate the potential effects of increased competition in the health care market. It pays particular attention to the effects of competition on the allocative efficiency of the health care system in terms of health care and health expenditures. Taken together, our results suggest that the canonical effects of competition do not necessarily apply to the health care market, and detail circumstances in which increased competition could harm social welfare. This thesis consists of an introduction and three chapters (academic papers), each focusing on a different aspect of health system efficiency. The first chapter analyzes the impact of competition on hospital care practices and their regulation through prospective pricing. The second chapter details the regulatory issues related to the incomplete nature of patient information when choosing which care procedure to adopt, starting with the decision to implement additional diagnostic tests. The final chapter of this thesis discusses the possible consequences of the asymmetry that may exist between public and private care providers in terms of coverage obligations and can be applied to the market for home care for the elderly.

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A government agency delegates to a provider (hospital, medical gatekeeper, school, social worker) the decision to supply a service or treatment to individual recipients. The agency does not perfectly know the distribution of individual treatment costs in the population. The single-crossing property is not satisfied when the uncertainty pertains to the dispersion of the distribution. We find that the provision of service should be distorted upward when the first-best efficient number of recipients is sufficiently high.

A government agency delegates to a provider (hospital, medical gatekeeper, school, social worker) the decision to supply a service or treatment to individual recipients. The agency does not perfectly know the distribution of individual treatment costs in the population. The single-crossing property is not satisfied when the uncertainty pertains to the dispersion of the distribution. We find that the provision of service should be distorted upwards when the first-best efficient number of recipients is sufficiently high.

Attention is a scarce resource. This study examines how users' limited attention affects the Internet advertising market. I analyze the Korean search engine market and present a structural estimate of the demand for banner ads that takes into account the limited attention of users. The theoretical model underlying this estimation assumes that users' attention is heterogeneously distributed. In this framework, I show that a monopoly platform tends to serve too many ads and that the probability of ads reaching their target depends on users' and websites' characteristics. A discrete choice model with random coefficients is used to estimate users' demand function. The two demand functions and the profit function of the platforms are used to derive the margin rate. The latter is composed of three components: a network effect on the user side, a congestion effect and the Lerner index.The reduced form estimation models are discussed as an introduction.They seem to reveal the existence of an information congestion phenomenon in the Korean search engine market.The structural estimation that I implement consists first of simulating the probability that a user pays attention to an advertisement posted on a Web site. The estimated model predicts the probability that a given advertisement will be perceived by the users of a website. The estimated model predicts the probability that a given advertisement will be perceived by the users of a website. This probability varies from 0.19 to 0.58 depending on the website and also varies according to the gender, age and education level of the users. A 1% increase in the number of ads displayed on a Web page results in a 0.06% decrease in the probability that an ad message will be perceived by users.The estimated user demand reveals that advertising is a nuisance for 92.17% of users. By estimating the demand for advertising, I conclude that the externality related to the limited attention of users is an important determinant of the margin rate of platforms.The study finally shows that the level of advertising on websites is systematically below the socially optimal level, which implies that the market power enjoyed by the sites leads to a restriction of the number of banner ads that goes beyond what would be socially optimal, given the negative externality of information congestion. This results in an increase in the advertisers' surplus but a decrease in the social surplus (deadweight loss).I finally perform a counterfactual experiment on the impact of ad blocking software. This experiment reveals that the generalization of such software reduces ad levels, because the valuation of users by a platform corresponds to the average number of advertising messages they receive. These results highlight that taking into account the phenomenon of information congestion is essential in estimating the demand for audiovisual content and advertising space.

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In Europe, competition authorities have the power to close antitrust cases with “commitment decisions” after the concerned firms have offered agreed remedies. We show that the optimal use of this instrument is governed by a tradeoff between deterrence of potentially anticompetitive practices and early restoration of effective competition. We relate the optimal policy to the distribution of firm profit and consumer harm among cases. We find, however, that the optimal policy is generally not enforceable when the authority cannot credibly announce its policy prior to the firms’ strategic decisions. The lack of authority credibility may translate into insufficient or excessive use of commitment decisions.

This article aims at understanding the interplay between pension schemes and tax instruments. The model features extensive labor supply in a stationary environment with overlapping generations and perfect financial markets. Compared with the reference case of a pure taxation economy, we find that taxes become more redistributive when the pension instrument is available, while pensions provide incentives to work.

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A government agency delegates to a provider (hospital, medical gatekeeper, school, social worker) the decision to supply a service or treatment to individual recipients. The agency does not perfectly know the distribution of individual treatment costs in the population. The single-crossing property is not satisfied when the uncertainty pertains to the dispersion of the distribution. We find that the provision of service should then be distorted upwards relative to efficiency when the (first-best) efficient number of recipients is sufficiently high.

In the first part of this thesis, we prove a weak version of the following conjecture, formulated in 1983 by Hildebrandt: in dimension 2, applications which are critical points of a conformal diffeomorphism invariant functional are regular. We show the regularity of such applications, provided that they are a priori bounded. This result extends the theorem of F. Helein on the regularity of harmonic applications with values in a compact riemannian variety without edge. The variational problems studied in the second part are motivated by economic questions. They consist in the maximization of some functionals on the cone of convex functions. We give a sufficient condition for the convexity constraint to be active. This condition, which involves in particular the geometry of the domain, is verified in very common situations in economics. Typically in dimension 2, there exists a region where the rank of the hessian of the solution is 1. We write the Euler equations of the problem using so-called "sweep" operators. We explain how to use the sweep conditions to construct the solution of the problem. However, this construction requires some prior knowledge of the form of the solution. This leads us to study the problem of the numerical approximation of the solution: the difficulty lies in determining the directions in which the convexity constraint is saturated. We explore various finite element methods and show that the simplest of them face a serious theoretical obstruction.