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Dans un environnement de plus en plus complexe, le besoin d'information des entreprises les incite à partager de nombreuses informations avec différents acteurs. Les échanges d'informations entre concurrents sont parmi les pratiques les plus subtiles appréhendées par le droit de la concurrence. Leur influence sur le processus concurrentiel a été mis en lumière par la théorie économique, et notamment la théorie de la collusion tacite qui a éclipsé, dans la pratique des autorités de concurrence, les autres pans de l'analyse économique traitant de la question. Or, cette littérature prolixe est d'un maniement difficile voire incertain. Leur traitement juridique a été en partie renouvelé par le rattachement de certains d'entre eux à la catégorie des restrictions objectives. Cependant, l'essentiel de ces pratiques restent évaluées par le biais d'une analyse multicritère complexe, économiquement colorée mais source d'une grande insécurité juridique. Néanmoins, il nous semble envisageable d'encadrer cette analyse multicritère afin d'aboutir à la prévisibilité juridique indispensable à l'heure de l'autoévaluation de leurs pratiques par les entreprises. / Nowadays, the complexity of markets incites undertakings to share much information with different kind of operators. Information exchanges between competitors are among the more subtle practices caught by the competition law. Their impact on the competition process has been highlighted by economic theory, and especially by tacit collusion theory which had outshined, in the competition enforcers’ practice, the other parts of economic theory dealing with this issue. Yet, this theory is difficult to use in an enforcement context. Recently, the enforcement of some of this information exchange has been renewed by their classification in the object box. Nevertheless, the main part of these practices is still assessed through a multi-criteria analysis with an economic coloration but with legal insecurity. Our point is that it seems possible to frame this analysis in order to give to firms the legal security they are needed at the time of self-assessment of their practices.

It was in 2004 that the first case study was done by on the ongoing Reverse Auction Bidding at Texas A&M University. This long-term study has developed from a single case study, completed by van Vleet, to a series of case studies, now combined with personality testing of all participants. van Vleet developed a Microsoft Access database system and Active Server Pages web based user interface for the study. The first case study involved five participants with no prior experience in Reverse Auction Bidding. A study with five participants is considered competitive in accordance with the standard economic Herfindahl Index. van Vleet, concluded that the results showed a level of co-operation in the bidding game between the nominal competitors. In 2010 John Nichols coined the term "tacit collusion" to identify this apparent behavioural pattern observed in the bidding. A significant element of the studies from 2005 to 2009 has been to investigate the "tacit collusion" behaviour. Tacit collusion is not considered an illegal economic behaviour. In 2006 Seth Gregory encountered significant problems with a study involving ten participants using the Access database, as a result of Access' limitations on the number of connections. Gregory's study was migrated to a Microsoft SQL database that was developed by Wellington (2006) and which overcame the limitations. SQL database systems can generate a significant quantity of data which create a computer science problem, now commonly termed 'Data rich - analysis poor'. This study is the first in a series of studies to undertake a detailed statistical study of the early case studies to provide a set of algorithms for development of SQL queries for automated real-time data analysis of future Reverse Auction Bidding case studies. This study showed that a fifth order polynomial fit the contract time compared to the job number. Analysis of the number of bids per minute for the fifteen minutes of bid time showed a log-polynomial equation which provided a reasonable fit to the data. Two sub-games were postulated to describe the operational aspects of the auction. The first game, termed the - game, is between the players with the objective of maximizing average return and the second game, termed the - game, has the objective of average cost minimization for the purchasers and maximization of revenue for the seller group. In conclusion, Reverse Auction Bidding systems are not bid shopping, but the tenet that the purchaser will reduce costs in this type of system compared to the traditional closed bid system is not confirmed with van Vleet's data and any careful consideration of the results of canny players in the 'game suggests higher than average returns for some bidders. The results show a number of patterns in the data that warrant further study, particularly the characteristics of the canny players in the alpha game suggests higher than average returns for some bidders. The results show a number of patterns in the data that warrant further study, particularly the characteristics of the canny players.

This dissertation comprises three essays on theoretical and empirical issues in industrial organization. Chapter 1 outlines the issues explored in the subsequent chapters and briefly describes their conclusions. Chapter 2 explores how product differentiation impacts the incentive compatibility condition for firms to sustain implicit collusion in games of repeated interaction where, in contrast to previous studies, I focus on a market which is simultaneously vertically and horizontally differentiated. To achieve this objective, vertical differentiation is incorporated into an otherwise standard Hotelling framework. The ensuing mixed model of differentiation shows how the interrelationships between both forms of differentiation impact the incentives to collude, and is more general since it replicates previous findings throughout the literature. In Chapter 3, a multiproduct oligopoly model admitting product differentiation and a discrete choice demand model are proposed and estimated to determine if patterns of anti-competitiveness exist across distinct segments of the European car market. This chapter focuses on the evolution of price competition at a finer level than has been studied with a view to empirically challenge the notion that the European car market is wholly anti-competitive. Empirical results show that firm conduct varies due to the intensity of within-segment competition among rival firms. There is evidence of softer competition in the larger, mid- to full-sized segments and more aggressive competition in the smaller, entry-level subcompact segment. Chapter 4 represents a formal extension of the analysis in Chapter 3. In this chapter I examine the competitive structure of the U.S. automobile market using proprietary data comprising actual dealer-level transaction prices of several models of cars and light trucks sold in the domestic U.S. market between 2004 and 2007. The chapter is the first such study to employ consumer end-prices for automobiles in a structural New Empirical Industrial Organization (NEIO) framework. Empirical results reveal that there is more aggressive pricing in the light truck segments comprising minivans/SUVs and pickups, Bertrand pricing in the smaller, entry-level car segments, and softer competition in the full-size car segment. There is also a strong preference for domestically produced light trucks although consumers generally prefer to drive fuel efficient vehicles. / Ph. D.

This thesis explores the emergence of functional collusion in groups and communities. Collusion is often taken up as synonymous with conspiracy, as a negative aspect of people seeking to get an advantage by nefarious means. In contrast, the thesis points to how a form of collusion might have a function for supporting people in their ongoing relating and in doing so suggests that there are two important factors in functional collusion. The first is that contextual history is key to understanding how, without planning or discussion, collusion emerges and is maintained in groups and communities. The second is that an absence of discussion is key because bringing collusive patterns of relating into our conversations disables their continuation. This thesis argues that collusion arises as people avoid the discomfort of emotions such as shame as well as maintaining familiar patterns of power relating. As collusive patterns of relating tend to emerge undiscussed between people, the thesis suggests that deciding whether to uncover and discuss them is a matter of contextual practical judgement or phronesis as it will inevitably require the navigation of ethical dilemmas which the author argues cannot be solved simply through the application of universal rules. This thesis offers a challenge to the way people working as organisational development practitioners think about their practice, especially those working in the not-for-profit sector.

This thesis examines the role of endogenous size processes in the stability and price setting decisions of cartels. Chapter One analyses how the stability of cartels de- pends on the level of horizontal product differentiation and on costs of collusion under the premise that a cartel can consist of less than all firms in an industry. It is shown that when the size of the cartel is determined endogenously, it is possible that increased costs of collusion make a cartel more stable. Chapter Two analyses how the price setting of firms in collusive industries is affected by three different penalty regimes: i) profits, ii) overcharge, and iii) revenue based penalties. It is found that penalties influence price setting in two ways: directly, by affecting the industry price for a given cartel size and indirectly by affecting cartel size and thereby the price charged. When the penalties are equally tough, in the sense that they deter cartels over the same group of products, over- charge based penalties always lead to the lowest prices, followed by prices computed under profits based penalties and then revenue based penalties. For very few combinations of product differentiation and market size, revenue based penalties lead to lower prices than profits based penalties. Finally, Chapter Three presents a model in which collusive stability is analysed in a dynamic setting of free entry, exit and mergers. Contrary to the previous literature it shows that stable and profitable collusion is possible under free entry, without the need for cartels to play entry deterring strategies. Furthermore, the empirical evidence that a breakdown of collusion can lead to increased merger activity is replicated. An additional contribution of this model is that it defines a new notion of a long run sustainable competitive market size under merger and entry.

Reverse auction bidding is an online auction system. A purchaser's primary objective in using a reverse auction is to obtain the lowest possible bid for goods and services on a construction project. With this type of bidding, it is normal that the purchaser will only consider price, instead of a bidders' work history and experience. As a reverse auction is an online service, the common misperception is that a purchaser can reach a broader market to obtain the lowest possible price. It is a controversial bidding system. No previous research has been undertaken by the Texas A&M University Reverse Auction Bidding study group into potential owner interference with the bidding system for a reverse auction. Six bidders were asked to participate in the Reverse Auction Bidding process for a series of construction projects in Houston. Each participant was also asked to complete a Keirsey Temperament Sorter Test type I and II to determine each participant's personality. After the tests, the six participants competed in an online reverse auction bidding game. The primary objective of this research is to analyze the impact of an owner's interference in a reverse auction bidding scenario. In this test, one of the six bidders acted as the owner's surrogate to interfere with an ethical process and reduce the owner's costs. The other five bidders were unaware of the surrogate's role in the bidding. The primary directive given to the surrogate bidder was to drive down the cost of the projects. The results for the research study show that the owner's surrogate can affect the bidding process. Interference results in reduced returns for the bidders when compared to an uncompromised bidding scenario. It is clear that the method used is unethical.

Participating in an auction and winning items by placing bids has been in practice since at least 500 B.C. Auctions have evolved since then and anyone can now participate in one online and buy items ranging from clothes, electronics, automobiles and homes using online auction websites, such as eBay. A Reverse Auction varies from the traditional style of Auction where items or services are won by placing successive higher bids until the auction ends. The study of Reverse Auction was first introduced to Texas A & M University in 2004 and continues today, using a SQL based web system. This current research provides a detailed statistical analysis of the fourth case study in this long running work. This fourth case study involved the participation of five bidders who had no prior experience in Reverse Auctions. A Microsoft Access database system and ASP web based user interface was developed and used to conduct these initial studies. However, due to the limited capability of the Access system to handle more than a limited number of connections or bidders, a Microsoft SQL database and web system was developed in 2006 and has been used in all subsequent studies. Case studies have involved up to ten participants. The results from the fourth case study show that a Reverse Auction can result in an increase in the average cost of the job to the owner. Also, there is evidence of game play amongst the bidders and against the purchaser that causes their profits to rise as they gain proficiency in the game. This behavior has been termed as 'tacit collision', but it is considered a byproduct of the system and not illegal behavior. This study analyzes the fourth study data to investigate if the behavior termed "tacit collusion" is evident in the bidding data. This analysis is completed by performing a detailed statistical analysis of the bidding data. Analysis of the profit percentages illustrates the different stages of the game play amongst the bidders. This game play behavior is illustrated by plotting average number of bids to the profit made by each bidder. The data clearly suggests that the players became efficient in their bidding strategy, although some bidders are more efficient than others. This observation negates the common conception that Reverse Auctions will result in lowering average costs for the owners. The individual data of bidders for bids and profit reveal why some players were able to obtain higher than average results and why the others were not. This study can be taken further by analyzing the patterns of the successful and unsuccessful players to determine what causes them to gain or lose profits.

In this thesis we present an effective steganalysis technique for digital video sequences based on the collusion attack. Steganalysis is the process of detecting with a high probability the presence of covert data in multimedia. Existing algorithms for steganalysis target detecting covert information in still images. When applied directly to video sequences these approaches are suboptimal. In this thesis we present methods that overcome this limitation by using redundant information present in the temporal domain to detect covert messages in the form of Gaussian watermarks. In particular we target the spread spectrum steganography method because of its widespread use. Our gains are achieved by exploiting the collusion attack that has recently been studied in the field of digital video watermarking and more sophisticated pattern recognition tools. Through analysis and simulations we, evaluate the effectiveness of the video steganalysis method based on averaging based collusion scheme. Other forms of collusion attack in the form of weighted linear collusion and block-based collusion schemes have been proposed to improve the detection performance. The proposed steganalsyis methods were successful in detecting hidden watermarks bearing low SNR with high accuracy. The simulation results also show the improved performance of the proposed temporal based methods over the spatial methods. We conclude that the essence of future video steganalysis techniques lies in the exploitation of the temporal redundancy.

Abstract This paper shows that collusive behavior of firms in production with lump-sum payment licensing may occur in an infinitely repeated duopoly if both firms adopt a two-period strategy to interact with each other. It is profitable for the patent-holding firm with non-drastic cost-reducing innovation to use licensing as a strategic means to induce the opponent to cooperate in pursuit of joint profit. It is proved that there exists a Pareto dominant two-period strategy profile, which is an equilibrium in both equilibrium and out-of-equilibrium paths. Furthermore, it is shown that the duration of punishment while two firms are in the out-of-equilibrium is endogenously determined.