Even though empirical studies show that political institutions affect various economic policies, standard economic models do not evaluate the effects of government ideology on the performance of state firms. I argue that state-owned enterprises (SOEs) are more efficient under center-right governments, while state firms under center-left cabinets show weaker performance. A modified Stackelberg oligopoly competition model that analyzes the proposed connection is developed. I, then, test implications from the model empirically using the case of Lithuania.

nÃo hà / This work aims to answer questions regarding the Brazilian aviation market, and how it behaves in terms of oligopolistic competition. That is, there are some firms in this sector competing for the same market, thereby analyzing issues among these firms, you may indicate issues of efficiency in this sector. Using data on market share of each company, and the elasticity of the aviation industry for the year 2009, it was mixed reviews on possible mergers in the airline market in Brazil, giving in each profile that elasticity which would potentially bring a greater distortion for the sector. The methodology for this was the model PCAIDS (Proportionality-Calibrated Almost Ideal Demand System), proposed by Epstein and Rubinfeld (2002) that simulates the merger of two companies in an oligopolistic market, and has an advantage of requiring fewer parameters to your pet than other methodologies. The findings suggest that the merger of GOL TAM will bring a higher price increases than other combinations that were made to give some scenarios that were tested. / Este trabalho visa responder questÃes referentes ao mercado de aviaÃÃo brasileiro e verificar como este se comporta em termos de concorrÃncia oligopolista. Ou seja, existem algumas firmas, neste setor, disputando o mesmo mercado, com isso, analisando questÃes entre essas firmas, à possÃvel indicar questÃes de eficiÃncia neste setor. Utilizando dados sobre a parcela de mercado de cada empresa, e as elasticidades do setor de aviaÃÃo para o ano de 2009, foram feitas vÃrias anÃlises sobre possÃveis fusÃes no mercado aÃreo brasileiro, indicando em cada perfil de elasticidade qual seria a que potencialmente traria uma maior distorÃÃo para o setor. A metodologia para tal processo foi o modelo PCAIDS (Proportionality-Calibrated Almost Ideal Demand System), proposto por Epstein e Rubinfeld (2002), que simula a fusÃo de duas empresas em um mercado oligopolizado, e possui uma vantagem de exigir menos parÃmetros para a sua estimaÃÃo do que as outras metodologias. As conclusÃes apontam que a fusÃo da empresa GOL com a TAM trarà uma maior elevaÃÃo de preÃos do que se outras combinaÃÃes fossem feitas para alguns cenÃrios de elasticidade que foram testados.

Die kumulative Dissertation beschäftigt sich mit stochastischen und deterministischen dynamischen Verkaufsmodellen für langlebige sowie verderbliche Güter. Die analysierten dynamischen Modelle sind durch die Möglichkeit der simultanen Variation von Preis und Werbung in stetiger Zeit charakterisiert und folgen den aktuellen Entwicklungen der Dynamischen Preissetzung. Dabei steht die Berücksichtigung und Analyse von (i) Zeitinhomogenitäten, (ii) Adoptionseffekten, (iii) Oligopolwettbewerb und (iv) der Risikoaversion des Entscheiders im Zentrum der Arbeit. Für die Spezialfälle isoelastischer und exponentieller Nachfrage in Verbindung mit isoelastischer Werbewirkung gelingt es explizite Lösungen der optimalen Preis- und Werbekontrollen herzuleiten. Die optimal gesteuerten Verkaufsprozesse können analytisch beschrieben und ausgewertet werden. Insbesondere werden neben erwarteten Preis- und Restbestandsentwicklungen auch assoziierte Gewinnverteilungen untersucht und Sensitivitätsresultate hergeleitet. Darüber hinaus wird analysiert unter welchen Bedingungen monopolistische Strategien sozial effizient sind und welche Besteuerungs- und Subventionsmechanismen geeignet sind um Effizienz herzustellen. Die Ergebnisse sind in sechs Artikel gefasst und bieten ökonomische Einsichten in verschiedene praktische Verkaufsanwendungen, speziell im Bereich des elektronischen Handels. / The cumulative dissertation deals with stochastic and deterministic dynamic sales models for durable as well as perishable products. The models analyzed are characterized by simultaneous dynamic pricing and advertising controls in continuous time and are in line with recent developments in dynamic pricing. They include the modeling of multi-dimensional decisions and take (i) time dependencies, (ii) adoption effects (iii), competitive settings and (iv) risk aversion, explicitly into account. For special cases with isoelastic demand functions as well as with exponential ones explicit solution formulas of the optimal pricing and advertising feedback controls are derived. Moreover, optimally controlled sales processes are analytically described. In particular, the distribution of profits, the expected evolution of prices as well as inventory levels are analyzed in detail and sensitivity results are obtained. Furthermore, we consider the question whether or not monopolistic policies are socially efficient; in special cases, we propose taxation/subsidy mechanisms to establish efficiency. The results are presented in six articles and provide economic insights into a variety of dynamic sales applications of the business world, especially in the area of e-commerce.