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Die Dissertation untersucht den Anteil der Armutsthematik an der Etablierung des Kinos in Deutschland. Der Untersuchungsschwerpunkt konzentriert sich auf die Jahre 1907 bis 1913, einer entscheidenden Zeitspanne für die Institutionalisierung des Kinos als Medium sui generis. Ziel der Untersuchung ist es, anhand von Filmanalysen wiederkehrende Muster medialer Praktiken der kinematographischen Artikulation der Sozialen Frage zu eruieren und ihre thematische Relevanz bzw. ihren Anteil für die Etablierung des Kinos in Deutschland zu bestimmen. Im Fokus stehen die Medienprodukte, ihre Motivgestaltung und Inszenierungspraktiken.
Stressinduzierte Veränderungen gastrointestinaler Peptidhormone könnten eine biologische Grundlage für Überessen und einen Faktor bei der Entstehung von Adipositas darstellen. Darum wurden die Veränderungen der Plasmakonzentrationen von Ghrelin und Peptid YY (PYY) durch akuten Stress bei 85 adipösen und normalgewichtigen Frauen untersucht. Im Vergleich zu normalgewichtigen Frauen hatten adipöse Frauen eine geringere pre- als auch postprandiale Ghrelin-Sekretion. Darüber hinaus fiel auch der postprandiale Ghrelin-Abfall bei den adipösen Frauen geringer aus als bei der normalgewichtigen Vergleichsgruppe. Akuter Stress inhibierte die PYY-Sekretion in beiden Gruppen. Außerdem wurde der Effekt von akutem Stress auf das Essverhalten erfasst. Stress inhibierte die Nahrungsaufnahme in beiden Gruppen.
Mittels Querschnittserhebungen ist es möglich Populationsparameter zu einem bestimmten Zeitpunkt zu schätzen. Jedoch ist meist die Veränderung von Populationsparametern von besonderem Interesse. So ist es zur Evaluation von politischen Zielvorgaben erforderlich die Veränderung von Indikatoren, wie Armutsmaßen, über die Zeit zu verfolgen. Um zu testen ob eine gemessene Veränderung sich signifikant von Null unterscheidet bedarf es einer Varianzschätzung für Veränderungen von Querschnitten. In diesem Zusammenhang ergeben sich oft zwei Probleme; Zum einen sind die relevanten Statistiken meist nicht-linear und zum anderen basieren die untersuchten Querschnittserhebungen auf Stichproben die nicht unabhängig voneinander gezogen wurden. Ziel der vorliegenden Dissertation ist es einen theoretischen Rahmen zur Herleitung und Schätzung der Varianz einer geschätzten Veränderung von nicht-linearen Statistiken zu geben. Hierzu werden die Eigenschaften von Stichprobendesigns erarbeitetet, die zur Koordination von Stichprobenziehungen in einer zeitlichen Abfolge verwendet werden. Insbesondere werden Ziehungsalgorithmen zur Koordination von Stichproben vorgestellt, erarbeitet und deren Eigenschaften beschrieben. Die Problematik der Varianzschätzung im Querschnitt für nicht-lineare Schätzer bei komplexen Stichprobendesigns wird ebenfalls behandelt. Schließlich wird ein allgemeiner Ansatz zur Schätzung von Veränderungen aufgezeigt und es werden Varianzschätzer für die Veränderung von Querschnittschätzern basierend auf koordinierten Querschnittstichproben untersucht. Insbesondere dem Fall einer sich über die Zeit verändernden Population wird eine besondere Bedeutung im Rahmen der Arbeit beigemessen, da diese im Anwendungsfall die Regel darstellen.
The classic Capital Asset Pricing Model and the portfolio theory suggest that investors hold the market portfolio to diversify idiosyncratic risks. The theory predicts that expected return of assets is positive and that reacts linearly on the overall market. However, in reality, we observe that investors often do not have perfectly diversified portfolios. Empirical studies find that new factors influence the deviation from the theoretical optimal investment. In the first part of this work (Chapter 2) we study such an example, namely the influence of maximum daily returns on subsequent returns. Here we follow ideas of Bali et al. (2011). The goal is to find cross-sectional relations between extremely positive returns and expected average returns. We take account a larger number of markets worldwide. Bali et al. (2011) report with respect to the U.S. market a robust negative relation between MAX (the maximum daily return) and the expected return in the subsequent time. We extent substantially their database to a number of other countries, and also take more recent data into account (until end of 2009). From that we conclude that the relation between MAX and expected returns is not consistent in all countries. Moreover, we test the robustness of the results of Bali et al. (2011) in two time-periods using the same data from CRSP. The results show that the effect of extremely positive returns is not stable over time. Indeed we find a negative cross-sectional relation between the extremely positive returns and the average returns for the first half of the time series, however, we do not find significant effects for the second half. The main results of this chapter serve as a basis for an unpublished working paper Yuan and Rieger (2014b). While in Chapter 2 we have studied factors that prevent optimal diversification, we consider in Chapter 3 and 4 situations where the optimal structure of diversification was previously unknown, namely diversification of options (or structured financial products). Financial derivatives are important additional investment form with respect to diversification. Not only common call and put options, but also structured products enable investors to pursue a multitude of investment strategies to improve the risk-return profile. Since derivatives become more and more important, diversification of portfolios with dimension of derivatives is of particularly practical relevance. We investigate the optimal diversification strategies in connection with underlying stocks for classical rational investors with constant relative risk aversion (CRRA). In particular, we apply Monte Carlo method based on the Black-Scholes model and the Heston model for stochastic volatility to model the stock market processes and the pricing of the derivatives. Afterwards, we compare the benchmark portfolio which consists of derivatives on single assets with derivatives on the index of these assets. First we compute the utility improvement of an investment in the risk-free assets and plain-vanilla options for CRRA investors in various scenarios. Furthermore, we extend our analysis to several kinds of structured products, in particular capital protected notes (CPNs), discount certificates (DCs) and bonus certificates (BCs). We find that the decision of an investor between these two diversification strategies leads to remarkable differences. The difference in the utility improvement is influenced by risk-preferences of investors, stock prices and the properties of the derivatives in the portfolio. The results will be presented in Chapter 3 and are the basis for a yet unpublished working paper Yuan and Rieger (2014a). To check furthermore whether underlyings of structured products influence decisions of investors, we discuss explicitly the utility gain of a stock-based product and an index-based product for an investor whose preferences are described by cumulative prospect theory (CPT) (Chapter 4, compare to Yuan (2014)). The goal is that to investigate the dependence of structured products on their underlying where we put emphasis on the difference between index-products and single-stock-products, in particular with respect to loss-aversion and mental accounting. We consider capital protected notes and discount certificates as examples, and model the stock prices and the index of these stocks via Monte Carlo simulations in the Black-Scholes framework. The results point out that market conditions, particularly the expected returns and volatility of the stocks play a crucial role in determining the preferences of investors for stock-based CPNs and index-based CPNs. A median CPT investor prefers the index-based CPNs if the expected return is higher and the volatility is lower, while he prefers the stock-based CPNs in the other situation. We also show that index-based DCs are robustly more attractive as compared to stock-based DCs for CPT investors.
Zum Einfluss von Transformationen schiefer Verteilungen auf die Analyse mit imputierten Daten
(2015)
Die korrekte Behandlung fehlender Daten in empirischen Untersuchungen spielt zunehmend eine wichtige Rolle in der anwendungsorientierten, quantitativen Forschung. Als zentrales flexibles Instrument wurde von Rubin (1987) die multiple Imputation entwickelt, welche unter regulären Bedingungen eine korrekte Inferenz der eigentlichen Schätzungen ermöglicht. Eine Reihe von Imputationsmethoden beruht im Wesentlichen auf der Normalverteilungsannahme. In der Empirie wird diese Annahme normalverteilter Daten zunehmend kritisiert. So erweisen sich Variablen auf Grund ihrer sehr schiefen Verteilungen für die Imputation als besonders problematisch. In dieser Arbeit steht die korrekte Behandlung fehlender Werte mit der Intention einer validen Inferenz der eigentlichen Schätzung im Vordergrund. Ein Instrument ist die Transformation schiefer Verteilungen, um mit Hilfe der transformierten und approximativ normalverteilten Daten Imputationen unter regulären Bedingungen durchzuführen. In der Arbeit wird ein multivariater Ansatz eingeführt. Anschließend wird im Rahmen mehrerer Monte-Carlo-Simulationsstudien gezeigt, dass der neue Ansatz bereits bekannte Verfahren dominiert und sich die Transformation positiv auf die Analyse mit imputierten Daten auswirkt.
Die vorliegende empirische Untersuchung nimmt eine gezielte Betrachtung der Auswirkungen des Working Capital Managements als Ganzem sowie seiner Teilkomponenten für die operative Profitabilität und das Bonitätsrating (d.h. im Ergebnis über seine Bedeutung für die Innen- und die Außenfinanzierung) deutscher mittelständischer Unternehmen vor. Darüber hinaus wird untersucht, in wie weit größenspezifische Unterschiede bei der Wirkung der einzelnen Komponenten des Working Capital Managements auf die operative Profitabilität und das Bonitätsrating bestehen, ob also die Stärke der ggf. zu beobachtenden Effekte für kleinere Unternehmen anders ausgeprägt ist als für größere Unternehmen. Zudem wird untersucht, ob sich die Stärke der zu beobachtenden Effekte in unterschiedlichen konjunkturellen Rahmenbedingungen jeweils verändert, um Erkenntnisse darüber zu gewinnen, ob und in wie weit Working Capital Management zur Verbesserung der Krisenresistenz mittelständischer Unternehmen beitragen kann.
In the first part of this work we generalize a method of building optimal confidence bounds provided in Buehler (1957) by specializing an exhaustive class of confidence regions inspired by Sterne (1954). The resulting confidence regions, also called Buehlerizations, are valid in general models and depend on a designated statistic'' that can be chosen according to some desired monotonicity behaviour of the confidence region. For a fixed designated statistic, the thus obtained family of confidence regions indexed by their confidence level is nested. Buehlerizations have furthermore the optimality property of being the smallest (w.r.t. set inclusion) confidence regions that are increasing in their designated statistic. The theory is eventually applied to normal, binomial, and exponential samples. The second part deals with the statistical comparison of pairs of diagnostic tests and establishes relations 1. between the sets of lower confidence bounds, 2. between the sets of pairs of comparable lower confidence bounds, and 3. between the sets of admissible lower confidence bounds in various models for diverse parameters of interest.
Part-time entrepreneurship has become increasingly popular and is a rather new field of research. Two important research topics are addressed in this dissertation: (a) the impact of culture on part-time and full-time entrepreneurship and (b) the motivational aspects of the transition from part-time to full-time entrepreneurship. Specifically, this dissertation advances prior research by highlighting the direct and indirect differential impact of macro-level societal culture on part-time and full-time entrepreneurship. Gender egalitarianism, uncertainty avoidance and future orientation have a significantly stronger impact on full-time than on part-time entrepreneurship. Furthermore the moderating impact of societal culture on micro-level relationships for both forms of entrepreneurship is explored. The age-old and well-established relationship between education and entrepreneurial activity is moderated by different forms of collectivism for part-time and full-time entrepreneurship. Regarding the motivation of part-time entrepreneurs to transition to full-time entrepreneurship, the entrepreneurial motives of self-realization and independence are significantly positively associated with the transition, whereas the entrepreneurial motives of income supplementation and recognition are significantly negatively associated with the transition. This dissertation advances academic research by indicating conceptual differences between part-time and full-time entrepreneurship in a multi country setting and by showing that both forms of entrepreneurship are impacted through different cultural mechanisms. Based on the findings, policy makers can identify the direct and indirect impact of societal culture on part-time and full-time entrepreneurship. As a result, policy makers can better target support and transition programs to foster entrepreneurial activity.
Service innovation has increasingly gained acknowledgement to contribute to economic growth and well-being. Despite this increased relevance in practice, service innovation is a developing research field. To advance literature on service innovation, this work analyzes with a qualitative study how firms manage service innovation activities in their organization differently. In addition, it evaluates the influence of top management commitment and corporate service innovativeness on service innovation capabilities of a firm and their implications for firm-level performance by conducting a quantitative study. Accordingly, the main overall research questions of this dissertation are: 1.) How and why do firms manage service innovation activities in their organization differently? 2.) What influence do top management commitment and corporate service innovativeness have on service innovation capabilities of a firm and what are the implications for firm-level performance? To respond to the first research question the way firms manage service innovation activities in their organization is investigated and by whom and how service innovations are developed. Moreover, it is examined why firms implement their service innovation activities differently. To achieve this a qualitative empirical study is conducted which included 22 semi-structured interviews with 15 firms in the sectors of construction, financial services, IT services, and logistics. Addressing the second research question, the aim is to improve the understanding about factors that enhance firm-level performance through service innovations. Deploying a dynamic capabilities perspective, a quantitative study is performed which underlines the importance of service innovation capabilities. More specifically, a theoretical framework is developed that proposes a positive relationship of top management commitment and corporate service innovativeness with service innovation capabilities and a positive relationship between service innovation capabilities and the firm-level performance indicators market performance, competitive advantage, and efficiency. A survey with double respondents from 87 companies from the sectors construction, financial services, IT services, and logistics was conducted to test the proposed theoretical framework by applying partial least squares structural equation modeling (PLS-SEM).
Matching problems with additional resource constraints are generalizations of the classical matching problem. The focus of this work is on matching problems with two types of additional resource constraints: The couple constrained matching problem and the level constrained matching problem. The first one is a matching problem which has imposed a set of additional equality constraints. Each constraint demands that for a given pair of edges either both edges are in the matching or none of them is in the matching. The second one is a matching problem which has imposed a single equality constraint. This constraint demands that an exact number of edges in the matching are so-called on-level edges. In a bipartite graph with fixed indices of the nodes, these are the edges with end-nodes that have the same index. As a central result concerning the couple constrained matching problem we prove that this problem is NP-hard, even on bipartite cycle graphs. Concerning the complexity of the level constrained perfect matching problem we show that it is polynomially equivalent to three other combinatorial optimization problems from the literature. For different combinations of fixed and variable parameters of one of these problems, the restricted perfect matching problem, we investigate their effect on the complexity of the problem. Further, the complexity of the assignment problem with an additional equality constraint is investigated. In a central part of this work we bring couple constraints into connection with a level constraint. We introduce the couple and level constrained matching problem with on-level couples, which is a matching problem with a special case of couple constraints together with a level constraint imposed on it. We prove that the decision version of this problem is NP-complete. This shows that the level constraint can be sufficient for making a polynomially solvable problem NP-hard when being imposed on that problem. This work also deals with the polyhedral structure of resource constrained matching problems. For the polytope corresponding to the relaxation of the level constrained perfect matching problem we develop a characterization of its non-integral vertices. We prove that for any given non-integral vertex of the polytope a corresponding inequality which separates this vertex from the convex hull of integral points can be found in polynomial time. Regarding the calculation of solutions of resource constrained matching problems, two new algorithms are presented. We develop a polynomial approximation algorithm for the level constrained matching problem on level graphs, which returns solutions whose size is at most one less than the size of an optimal solution. We then describe the Objective Branching Algorithm, a new algorithm for exactly solving the perfect matching problem with an additional equality constraint. The algorithm makes use of the fact that the weighted perfect matching problem without an additional side constraint is polynomially solvable. In the Appendix, experimental results of an implementation of the Objective Branching Algorithm are listed.