The first essay provides an introduction into the literature of spatial competition models and studies their predictions on the degree of horizontal product differentiation. For this purpose a selection of articles, mainly from the game theoretical strand of the literature, is re-examined in which each model extends and modifies basic parameters of the original model of Hotelling (1929). The literature survey emphasizes that markets consisting of intersecting roads represent a particular fruitful subject of future research. The nature of competition in this market setting is different compared to the linear city exemplified by the importance of asymmetrical location patterns. Consequently, the strategic interaction, firms' profit-maximizing behavior and potential equilibrium outcomes under sequential entry in a market with intersecting roads remain to be an interesting field to study. The second essay addresses this research gap and based on the work of Anderson (1987) studies a two-stage market entry game in a spatially extended Hotelling's duopoly. Particularly, the effect of a demand dependent centrality bonus Z distributed in the middle of the linear city is examined on the reaction functions of an incumbent firm and the strategic entry decision of an entrant firm. A solution is provided for an entry accommodating scenario where both players optimize profits over their strategic variables and the center Z is taken by the incumbent firm. The results further suggest that the entrant is not capable of capturing Z. In addition, the model implies a lower degree of product differentiation as Z increases. A comparison with the literature shows that these results are well in line with Anderson's model for Z = 0. In a business strategy view the outcome supports the thesis of Gelman & Salop (1983), coined by the term 'judo economics', since the entrant earns highest profits by committing himself to a distant location and charging a comparatively lower price than the incumbent. The third essay analyzes the price distribution of diesel in the Austrian retail gasoline market and tests predictions of the impact of the fraction of informed and uninformed consumers on the mean price and price variance. Further, introducing two measures of spatial competition, the relation of local competition between stations and the mean and variance are examined. In a pooled cross-section analysis a two step approach is followed. Initially, price levels are estimated with respect to the influence of competition, search costs, stations' location and further station-specific characteristics. Controlling for these observable price characteristics, the residuals are used in the second step to investigate the behavior of the price variance. In addition to OLS, to account for spatial spillover effects a Spatial Error Model (SEM) is applied to estimate the price function. Additionally, tests on model specification and robustness checks using different weighting matrices, search cost proxies and dispersion measures are carried out. The results reveal a negative (positive) correlation between the fraction of informed (uninformed) consumers and the mean price. Further, price variance shows an inverse U-shape with the fraction of informed consumers. Thus, the variance initially increases as the proportion of informed consumers increases and starts to decline after the share of informed exceeds a threshold of roughly 43%. These findings are in line with predictions of classical search models, most notably Stahl (1989), and empirically support the meaning of consumer search in the context of oligopolistic pricing. Further, the mean price decreases as competition intensifies whereas the Price variance increases under increased entry competition (Janssen & Moraga-Gonzalez (2004), Carlson & McAfee (1983)). This suggests stations' tendency to focus more strongly on the lower price segment as competition increases.

隨著分工日細，廣告業從以往附屬於生產公司的一個部門，逐漸轉變為一項專門的產業，在商品競爭中佔有舉足輕重之地位。然而隨著廣告業的蓬勃發展，消費者卻對廣告日漸疏離，產生不信任感，為了贏得消費者的青睞，廠商開始採行代言式廣告，以中立的第三者或是對消費者具有魅力的代言人為商品背書，希望藉此增加產品之銷售量。 回顧文獻發現以往學者多著重於討論廣告之最適數量及效果、廠商的定位問題或代言人之人格、行為對產品銷售量之影響，而較少探討代言成本的問題，也缺乏對於參考群體有背書範圍之討論，因此本文將代言成本列入考量，發現考慮代言成本後，有助於促使廠商作誠實廣告，且代言成本越高，對廠商及消費者越有利，因而政府的查緝不實廣告行動，有助於增進社會福利。 在參考群體的背書範圍上，本文亦作背書差異之探討，發現廠商是否得到利益團體之背書，並不必然影響廠商之售價與利潤，以馬英九未來的從政之路以及大同、可口可樂之行銷策略進行佐證，皆指出廠商會避免被消費者視為邊緣產品，因而當參考群體的位置過於偏頗時，未受推薦反而對廠商有利。

Thesis (Ph. D.)--University of Wisconsin--Madison, 1976. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Bachelor-Arbeit Univ. St. Gallen, 2004.

No description available.

Chapter 2 deals with a linear city model à la Hotelling where the two firms share linear transport costs with their customers. Mill pricing and uniform delivery pricing are special limiting cases. We characterize the conditions for the existence of a pure strategy equilibrium in the two-stage location-price game. These enable us to identify the causes for non-existence in the two limiting cases. We solve for the equilibrium of a location game between the duopolists with an exogenously given price. When the two firms are constrained to locate at the same central spot, we show the nonexistence of pure strategy equilibria, conjecture the existence of mixed strategy equilibria, and show that any such possible equilibria will always yield positive expected profits. Chapter 3 provides simulations as well as theoretical analysis of potential spatial separation of heterogeneous agents operating on a two-dimensional grid space that represents a city. Heterogeneity refers to a characteristic which is also a determinant of individual valuation of land. We study spatial separation with respect to the distinguishing characteristic and investigate the details of emerging spatial patterns. Simulations suggest that the process of interaction with little trade friction goes through stages which resemble its end-state with high trade friction. Several theoretical examples exhibit a distinguishing characteristic upon which the simulations are based. They reflect some of the causes for spatial separation. Examples for the absence of spatial separation are also given. In Chapter 4 simulations, in addition to some theory, are used to investigate certain aspects of a city formation process. The model assumes two types of economic agents, workers and employers, operating on a two-dimensional grid. The agents have simple preferences, positive for the opposite type and negative for the own type in the own location. In addition, they have positive or negative preference for agglomeration in the own location. The model helps build intuition about a potentially important factor for agglomeration formation, namely, the disparity between entrepreneurial and technical skills in localities. We also determine the minimum level of positive preference for agglomeration that leads to agglomeration formation. / Ph. D.

L’épuisement des énergies fossiles est un thème d’actualité dont les prémices datent, selon l’opinion courante, des années 1970 et du premier choc pétrolier. En réalité, c’est une préoccupation plus ancienne, intimement liée à l’ère industrielle. Dans la deuxième partie du XIXème siècle, les économistes se sont penchés sur la question de l'épuisement des minerais, ‘objet non identifié’ jusqu'alors et nécessitant la mise sur pied de nouveaux outils d'analyse (effet-rebond chez Jevons, rente minière chez Marshall-Einaudi notamment). Avec le progrès des techniques et l'apparition de nouvelles énergies (pétrole, hydro-électricité), leurs craintes de déclin industriel se sont progressivement dissipées dans les années 1910 et 1920. Mais ces évolutions tenant à l’histoire des faits ne sont pas les seules à considérer. Des facteurs internes à la discipline économique, comme l'émergence du marginalisme dans les années 1870 et de la théorie de l'épargne et du capital dans les années 1890, ont aussi changé le regard des économistes sur la question de l'épuisement des ressources. Pourquoi ? Comment ? Quels enseignements peut-on en tirer pour les défis environnementaux d'aujourd'hui ? Voilà les questions qui sont traitées dans ce travail de thèse. / Fossil fuels exhaustion is a current topic. It is often said that its first presages appeared in the 1970s with the first oil shock. Actually, this exhaustion fear is much older than that, it started with the Industrial Revolution and kept going since then. In the second part of the 19th century, some economists focused their attention on the mineral resources depletion, which was at the time an ‘unknown item’ that necessitated the creation of new concepts and new analytical tools to deal with (for example Jevons’ rebound-effect, Marshall-Einaudi’s mining rent). In the 1910s and 1920s, thanks to technical progress and the development of new energies (oil, hydro-electricity), their fears about industrial decline progressively dissipated. Yet, these factual evolutions are not the only ones to consider. Internal factors, inside economic science (marginalism in the 1870s, capital theory in the 1890s), also shaped economists’ viewpoint on resources exhaustion. Why? How? What lessons can we get from this period for our current environmental challenges? These are the questions that are studied in this thesis.

Cette thèse en économie de l'énergie et de l'environnement étend le modèle de Hotelling du type exploration-extraction avec contraintes géologiques d’Okullo, Reynes et Hofkes (2015), afin de prendre en compte des trajectoires en forme de cloche pour l’ajout de réserves empiriquement observées par Laherrère (2003). Le modèle LOGIMA proposé (Images à Long terme sur le Pétrole et le Gaz) explique qu’elles sont la conséquence de « sweet spots » géologiques : des zones privilégiées où la concentration d’hydrocarbures est la plus élevée. Le modèle LOGIMA a été calibré sur une base de données issues couvrant les sept principaux bassins de pétrole et de gaz non-conventionnels du pays. Les résultats indiquent que la nécessité d’apprentissage par la pratique pour découvrir l’emplacement des sweet spots conduit à une mise en œuvre d’un effort d’exploration également en forme de cloche, ce qui permet de réduire le risque des activités d’exploration. Par conséquent, la réponse en termes des volumes offerts par les producteurs à des chocs sur les prix dévient fonction de l’ensemble des ressources mondiales antérieurement découvertes. Ensuite, nous appliquons le modèle LOGIMA pour étudier l’impact causé par l’offre de pétrole et de gaz naturel « non-conventionnels » aux États-Unis, sur les efforts mondiaux d’atténuation du changement climatique. Nous y parvenons en associant les scénarios à long-terme générés par LOGIMA avec le modèle d’évaluation intégrée, IMACLIM-R. Cette étude analyse comment des différentes cibles de prix de pétrole affecteraient son offre aux États-Unis. Nous estimons cette interaction au moyen de trois cadres de politiques en matière de climat : le cadre « business as usual » (BAU), les contributions décidées à l’échelle nationale (NDC) et les scénarios de 2°C (2DS). Les résultats de l’exercice indiquent que les approvisionnements non-conventionnels sont fortement susceptibles d’affecter les marchés énergétiques mondiaux, mais leur impact sur les émissions mondiales de gaz à effet de serre serait limité, car les différents effets déclenchés dans des différents secteurs viendraient les équilibrer approximativement. / This thesis in energy and environmental economics extends the geological Hotelling-type extraction-exploration model from Okullo, Reynes and Hofkes (2015) in order to account for the bell-shaped reserve additions that were empirically observed by Laherrère (2003). The proposed model explains them as the result of geological “sweet spots”: premium areas within geological formations where the concentration of hydrocarbons is highest. The proposed theoretical formulation was programmed into the mathematical model LOGIMA – “Long-term Oil and Gas Images” – and calibrated on data covering the seven main unconventional oil and gas plays in the United States. Results indicate the need to learn the location of sweet spots through trial and error drillings leads to schedules of exploratory effort that allow the optimal “de-risking” of exploratory activities. As a result, the optimal response of producers to price shocks becomes contingent on the prevailing level of cumulative discoveries.We apply LOGIMA to investigate the impact, caused by the recent advent of large-scale supplies of unconventional oil and gas, in the United States, on the ongoing efforts to mitigate climate change. We do so by soft coupling long-term scenarios from LOGIMA with the integrated assessment model, IMACLIM-R, a recursive, computable general equilibrium model of integrated global energy, economy and environment systems. We analyze how different price targets, potentially pursued by the Organization of Petroleum Exporting Countries (OPEC), would affect supplies of unconventional oil and gas from the United States. We control this interplay under three climate policy frameworks: business as usual (BAU), nationally determined contributions (NDCs) and 2°C scenario (2DS). The results of the exercise show that, despite having a significant potential to affect global energy markets, unconventional oil and gas supplies would have a limited potential to affect global cumulative greenhouse gas emissions to 2040, as the different effects triggered in different sectors approximately balanced each other out.

This thesis is concerned with game-theoretic models of oligopoly resource markets. They revolve around an open market, on which a number of firms sell a common resource. The market price-demand relationship means that the price (demand) that results from the firm’s production (pricing) decisions is a function of the decisions of all firms selling to that market. This means that firms must generally anticipate the actions of competing firms when determining their own strategies, which means that these models often need to be analysed using game theory. We focus on games in which the resource is exhaustible, with the exception of Chapter 5, in which the majority of the analysis is carried out in an inexhaustible resources setting. Exhaustibility introduces an additional complication into these games; that of allocating the extraction and sale of a limited resource pool over time. We consider several separate areas of extension, which we outline below. In Chapter 2, we consider a dynamic Stackelberg game. Stackelberg competition is an asymmetric form of competition in which one player (the leader) has the ability to pre-commit to and announce a strategy in advance. The ability to pre-commit to a strategy is almost always highly valuable, and in this case allows the leader to drive down the follower’s production by pre-committing to drive up their own. We follow the framework used in [62] to analyse Cournot competition to derive our results. In Chapter 3, we compare the two settings in which resource extraction models are usually formulated: Open-Loop, in which the players determine their strategies as functions of time and the initial resource levels of the players only; and Feedback-Loop, in which the players determine their strategies at each point in time as a function of the current resource levels at that time. Our focus is on the investigation of the relationship between the difference in the production or value of a firm under these two models, and the distribution of resources across the firms. In Chapter 4, we consider a common property resource game. These involve multiple firms which can extract from a common resource pool. We study a widely-used Open- viii Loop model, as formulated in [79]. We examine the result that analysis of the problem by standard methods results in two candidate equilibria, and argue that one of these equilibria can be ruled out by construction of a superior response. In Chapter 5, we analyse joint constraints on production, namely constraints which are met when the total production is above or below a certain level. It is a well- established result that these constraints can result in multiple equilibria. We provide several brief extensions to existing uniqueness results. We also demonstrate methods by which these results can be utilised to analyse games with piecewise-linear windfall taxes or congestion charges. Finally, we discuss the problems of extending these results to games with resource exhaustibility.

Chronic liver disease is a worldwide health problem, and hepatic fibrosis (HF) is one of the hallmarks of the disease. Pathology diagnosis of HF is based on textural change in the liver as a lobular collagen network that develops within portal triads. The scale of collagen lobules is characteristically on order of 1mm, which close to the resolution limit of in vivo Gd-enhanced MRI. In this work the methods to collect training and testing images for a Hotelling observer are covered. An observer based on local texture analysis is trained and tested using wet-tissue phantoms. The technique is used to optimize the MRI sequence based on task performance. The final method developed is a two stage model observer to classify fibrotic and healthy tissue in both phantoms and in vivo MRI images. The first stage observer tests for the presence of local texture. Test statistics from the first observer are used to train the second stage observer to globally sample the local observer results. A decision of the disease class is made for an entire MRI image slice using test statistics collected from the second observer. The techniques are tested on wet-tissue phantoms and in vivo clinical patient data.