In the literature on contests, punishments have received much less attention than prizes. One possible reason is that punishing the bottom player(s) in a contest where all contestants are not allowed to quit, while effective in increasing contestants' total effort, often violates individual rationality constraints. But what will happen in an open contest where all potential contestants can choose whether or not to participate? In chapter 1, we study a model of this type and allow the contest designer to punish the bottom participant according to their performances. We conclude that punishment is often not desirable (optimal punishment is zero) when the contest designer wants to maximize the expected total effort, while punishment is often desirable (optimal punishment is strictly positive) when the contest designer wants to maximize the expected highest individual effort. In the literature on imperfectly discriminating contests, researchers normally assume that the contest designer has a certain level of accuracy in choosing the winner, which can be represented by the discriminatory power r in the Power Contest Success Function (the Power CSF, proposed by Tullock in 1980). With symmetric contestants, it is well known that increasing accuracy (r) always increases total effort when the pure-strategy equilibrium exists. In chapter 2, we look at the cases where the contestants are heterogeneous in ability. We construct an equilibrium set on r > 0, where a unique pure-strategy equilibrium exists for any r below a critical value and a mixed-strategy equilibrium exists for any r above this critical value. We find that if the contestants are sufficiently different in ability, there always exists an optimal accuracy level for the contest designer. Additionally, as we increase the difference in their abilities, the optimal accuracy level decreases. The above conclusions provide an explanation to many phenomena in the real world and may give guidance in some applications. In chapter 3, we propose the Power Contest Defeat Function (the Power CDF)which eliminates one player out at a time over successive rounds. We show that the Power CDF has the same good qualities as the Power Contest Success Function (the Power CSF) and is more realistic in some cases. We look at both the Power CSF mechanism (selecting winners in sequence) and the Power CDF mechanism (selecting losers in sequence) and show that punishments increase expected total e¤orts signi cantly. More interestingly, we also find that when the contestants' effort levels are different, the Power CDF mechanism is more accurate in finding the correct winner (the one who makes the greatest effort) and the Power CSF mechanism is more accurate in finding the correct loser (the one who makes the smallest effort).

Cette thèse traite de l'analyse économique des conflits, et plus particulièrement de l'apport d'une méthode, la "Contest Theory". En partant du postulat simple que les agents économiques réalisent un arbitrage beurre-canons, les conflits ont pu être intégrés dans le champ de l'analyse économique. Dans le premier chapitre, nous proposons une synthèse des principaux résultats et nous décrivons le rôle décisif des Contest Success Functions dans ce cadre théorique. Le second chapitre montre que, pour traiter des conflits armés, l'identité institutionnelle des agents devrait davantage être pris en considération dans les modèles de la "Contest Theory". Le troisième chapitre s'intéresse aux motivations pouvant expliquer le commerce d'armes entre ennemis. Nous montrons que si le vendeur dispose d'une technologie militaire et non militaire plus efficace que l'acheteur, le commerce d'armes peut s'avérer mutuellement avantageux. Dans le quatrième chapitre nous proposons d'estimer et de comparer les quatre plus grandes formes de Contest Success Functions en recourant à des données provenant du monde virtuel. À partir d'un échantillon de 1957 batailles, nous trouvons que la forme ratio est celle qui a la plus grande qualité prédictive. En d'autres termes, le principal facteur expliquant la victoire sur un champ de bataille (virtuel) est le ratio du nombre de canons déployés. / This thesis deals with conflict economics, and more precisely with the contributions of the Contest Theory to the field. This method assumes that economic agents face a trade off between guns and butter's activities. By doing so, it allows the consideration of conflicts in economic mainstream. In the first chapter, we offer a survey on guns versus butter models. In particular, we focus on Contest Success Functions which are the cornerstone of the framework. The second chapter highlights one limit of the models of contest theory in conflict economics namely the lack of importance given to the identity of agents. The third chapter studies the motivation which can explain the existence of arms trade between enemies. We show that if the seller has a higher productivity both in guns and butter's activity, there exists a mutually benefficial agreement. As a result, even between enemies, arms trade may be rational. In the fourth chapter, we estimate and compare the four main forms of Contest Success Functionsusing data coming from virtual worlds. Based on a sample of 1957 (virtual) battles, we find that the ratio form is always the best-fit Contest Success Function.

In this series of essays, we study the influence of weight and group size in the sequential multi-battle contest with laboratory experiences (Chapter 2 and Chapter 3). We then develop an empirical method to model perceptual present and time inconsistency (Chapter 4). Chapter 2 examines how the weight and the ordered weights in battles affect the behavior in sequential multi-battle contests with an experiment. We find robustly that the weight of the current battle consistently influences contestants' efforts. Additionally, we discover the math-point-oriented behavior despite differences in history. In other words, the weight effect is expressed in two ways: influencing the effort of the current battle and transferring a contest to the next battle with a designated intensity. Chapter 3 explores the group size effect and how the contest success functions influence the group size effect in sequential multi-battle contests with an experiment. We capture the negative group size effect on the leaders' efforts, participation and dropout rates; contrarily, the positive effect on the non-leaders' efforts. Compared to the Tullock lottery, the all-pay auction intensifies the group size effect of the high effort in the initial battle. It also enlarges the observed group size effects of the effort gaps between the leaders and the non-leaders. Chapter 4 develops the quasi-hyperbolic discounting model into the general beta-delta model to parametrically detect and measure the inconsistency in revealed time preference. This method empirically classifies time preference into four categories, i.e., time consistent, present bias, future bias, and mixed inconsistent. Then we applied this method to the convex time budget data of seven experiments, including 3670 subjects. We discover empirical evidence supporting perceptual differences in the present-future threshold. Traditional present bias models may interpret the time preference imprecisely. / Doctor of Philosophy / Competition and Time are two essential aspects of life. Many decisions are made in a competitive environment. Some other decisions are made when time serves as a critical factor. We divide this dissertation into two parts. In the first part, we study strategic behavior in competitions. Specifically, we examine how (1) the importance of each round (weight), (2) the number of competitors, and (3) the ambiguity of the rule affect the result of a multi-round competition. In the second part, we study people's subjective understanding of time, generally the personal beliefs and preferences of the present and future. In part one (Chapter 2 and Chapter 3), first, we find people are very responsive about the importance of a round in a multi-round competition. When a round is more important, people make more effort in such round. People are also sensible about the competition's current status (leading, behind, or tied) rather than the history. Second, at the beginning of a competition, we find an increase in the participation rate when fewer competitors exist. Suppose there are more competitors; the leading position players compete more brutally; on the contrary, the non-leading players are discouraged more. Third, people spend more energy when the rule is less ambiguous in a multi-round competition. In part two (Chapter 4), We find a very diversified subjective belief in the word "present." The concept of "now" lasts longer than we conventionally thought. When the subjective "present'' is captured at the individual level, we find the immediate now is not necessarily the best way to represent the "average present'' for the population.

This dissertation focuses on studying various network formation games in Economics. We explore a different model in each chapter to capture various aspects of networks. Chapter 1provides an overview of this dissertation. Chapter 2 studies the possible Nash equilibrium configurations in a model of signed network formation as proposed by Hiller (2017). We specify the Nash equilibria in the case of heterogeneous agents. We find 3 possible Nash equilibrium configurations: Utopia network, positive assortative matching, and disassortative matching. We derive the specific conditions under which they arise in a Nash equilibrium. In Chapter 3, we study a generalized model of signed network formation game where the players can choose not only positive and negative links but also neutral links. We check whether the results of the signed network formation model in the literature still hold in our generalized framework using the notion of pairwise Nash equilibrium. Chapter 4 studies inequality in a weighted network formation model using the notion of Nash equilibrium. As a factor of inequality, there are two types of players: Rich players and poor players. We show that both rich and poor players designate other rich players as their best friends. As a result, We present that nested split graphs are drawn from survey data because researchers tend to ask respondents to list only a few friends. / Doctor of Philosophy / This dissertation focuses on studying various network formation games in Economics. We explore a different model in each chapter to capture various aspects of networks. Chapter 1 provides an overview of this dissertation. Chapter 2 studies the possible singed network configurations in equilibrium. In the signed network, players can choose a positive (+) relationship or a negative (-) relationship toward each other player. We study the case that the players are heterogeneous. We find 3 possible categories of networks in equilibrium: Utopia network, positive assortative matching, and disassortative matching. We derive the specific conditions under which they arise in equilibrium. In Chapter 3, we study a generalized model of signed network formation game where the players can choose not only positive and negative links but also neutral links. We check whether the results of the signed network formation model in the literature still hold in our generalized framework. Chapter 4 studies inequality in a weighted network formation model using the notion of Nash equilibrium. In this weighted network model, each player can choose the level of relationship. As a factor of inequality, there are two types of players: rich players and poor players. We show that both rich and poor players choose other rich players as their best friends. As a result, we present that nested split graphs are drawn from survey data because these social network data are censored due to the limit of the number of responses.

This dissertation focuses on the sub-national impact of foreign aid on civil conflicts by asking the question: How does foreign aid committed to contested areas affect the intensity of violence in those areas? The main theoretical contribution is to focus on how aid influences warring parties’ decisions to engage in contests over territorial control and how that in turn influences violence intensity. The study introduces two concepts: funding concentration and barriers to exploiting aid. A contested area has greater concentration of funding if warring parties expect a high value of aid to be distributed to only a few locations. Funding is instead diffused if the parties expect aid to be spread over many locations. A low barrier to exploiting aid is present if it is of a type that both state and non-state actors could potentially misuse. There is a high barrier if territorial control is required in order to exploit funding channels. The theory introduces three testable implications: First, greater funding concentration encourages conventional contests over territorial control, which increases military fatalities. The second proposal is that if there is a low barrier to exploiting aid (e.g. humanitarian and food aid) then there will be increased competition between warring parties and civilians, and hence more civilian fatalities. Third, high barrier funding (e.g. education aid) will motivate contests over territorial control and increase military fatalities. This dissertation uses geo-coded aid commitments data and introduces data of warring parties’ battleground control in sub-Saharan Africa, 1989–2008. The research design relies on propensity score matching where pairs of observations are matched based on a range of covariates. The results concerning barriers to exploitation are partially supported. High barrier aid increases military fatalities whereas low barrier aid has little impact on violence. Greater funding concentration increases military fatalities substantially compared to if there is low or no funding concentration. In line with theory, greater funding concentration does not increase civilian fatalities.