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Robustness of centrality measures (2020)

Martin, Christoph

Network analysis methods have long been used in the social sciences. About 25 years ago, these methods gained popularity in various other domains and many real-world phenomena have been modeled using networks. Well-known examples include (online) social networks, economic networks, web graphs, metabolic networks, infrastructure networks, and many more. Technological development made it possible to store and process data on a scale not imaginable decades ago — a development that also includes network data. A particular characteristic of network data is that, unlike standard data, the objects of interest, called nodes, have relationships to (possibly all) other objects in the network. Collecting empirical data is often complicated and cumbersome, hence, the observed data are typically incomplete and might also contain other types of errors. Because of the interdependent structure of network data, these errors have a severe impact on network analysis methods. This cumulative dissertation is about the impact of erroneous network data on centrality measures, which are methods to assess the position of an object, for example a person, with respect to all other objects in a network. Existing studies have shown that even small errors can substantially alter these positions. The impact of errors on centrality measures is typically quantified using a concept called robustness. The articles included in this dissertation contribute to a better understanding of the robustness of centrality measures in several aspects. It is argued why the robustness needs to be estimated and a new method is proposed. This method allows researchers to estimate the robustness of a centrality measure in a specific network and can be used as a basis for decision making. The relationship between network properties and the robustness of centrality measures is analyzed. Experimental and analytical approaches show that centrality measures are often more robust in networks with a larger average degree. The study of the impact of non-random errors on the robustness suggests that centrality measures are often more robust if missing nodes are more likely to belong to the same community compared to missingness completely at random. For the development of imputation procedures based on machine learning techniques, a process for the evaluation of node embedding methods is proposed.

Essays in empirical population economics (2020)

Petrunyk, Inna

My dissertation embraces four empirical papers addressing socio-economic issues relevant to policy-makers and society as a whole. These papers cover important aspects of human life including health at birth, life satisfaction, unemployment periods and retirement decisions, and are intended to provide a contribution to the respective research areas. The analyses are carried out applying advanced econometric methods and are based on data sets consisting of survey data as well as administrative records. The joint paper with Alessandro Palma and Daniela Vuri "Prenatal Air Pollution Exposure and Neonatal Health" in Chapter 2 investigates the causal impact of prenatal exposure to air pollution on neonatal health in Italy in the 2000s combining detailed information on mother’s residential location from birth certificates with PM10 concentrations from air pollution monitors. Variation in local weekly rainfall is exploited as an instrumental variable for non-random air pollution exposure. Using quasi-experimental variation in rainfall shocks allows to identify the effect of PM10, ruling out potential bias due to confounder pollutants. The paper estimates the effect of exposure for both the entire pregnancy period and separately for each trimester to test whether the neonatal health effects are driven by pollution exposure during a particular gestation period. This information enhances our understanding of the mechanisms at work and help prevent pregnant mothers from most dangerous exposure periods. Additionally, the effects of prenatal exposure to PM10 are estimated by maternal labor market status and maternal education level to understand how the pollution burden is shared across different population groups. This decomposition allows to identify possible mechanisms through which environmental inequality reinforces the negative impact of early-life exposure to air pollution. This study finds that average PM10 and days with PM10 level above the hazard limit reduce birth weight, gestational age, and measures of overall newborn health. Effects are largest for third trimester exposure and for low-income and less educated mothers. These findings imply that further policy efforts are needed to fully protect fetuses from the adverse effects of air pollution and to mitigate the environmental inequality of health at birth. The joint paper with Christian Pfeifer "Life Satisfaction in Germany After Reunification: Additional Insights on the Pattern of Convergence" in Chapter 3 updates previous findings on the total East-West gap in overall life satisfaction and its trend by using data from the German Socio-Economic Panel for the years 1992 to 2013. Additionally, the effects are separately analyzed for men and women as well as for four birth cohorts. The results indicate that reported life satisfaction is, on average, significantly lower in East than in West German federal states and that part of the raw East-West gap is due to differences in household income and unemployment status. The conditional East-West gap decreased in the first years after the German reunification and remained quite stable and sizable since the mid-nineties. The results further indicate that gender differences are small. Finally, the East-West gap is significantly smaller and shows a trend towards convergence for younger birth cohorts. The joint paper with Christian Pfeifer "Unemployment Benefits Duration and Labor Market Outcomes: Evidence from a Natural Experiment in Germany" in Chapter 4 explores the effects 2 of a major reform of unemployment benefits in Germany on the labor market outcomes of individuals with some health impairment. The reform induced a substantial reduction in the potential duration of regular unemployment benefits for older workers. This work analyzes the reform in a wider framework of institutional interactions, which allows to distinguish between its intended and unintended effects. The results based on routine data collected by the German Statutory Pension Insurance and a Difference-in-Differences design provide causal evidence for a significant decrease in the number of days in unemployment benefits and increase in the number of days in employment. However, they also suggest a significant increase in the number of days in unemployment assistance, granted upon exhaustion of unemployment benefits. Transitions to unemployment assistance represent an unintended effect, limiting the success of a policy change that aims to increase labor supply via reductions in the generosity of the unemployment insurance system. The single-authored paper "How Older Workers Respond to Raised Early Retirement Age: Evidence from a Kink Design in Germany" in Chapter 5 explores how an increase in the early retirement age affects labor force participation of older workers. The analysis is based on a social security reform in Germany, which raised the early retirement age over several birth cohorts to boost employment of older people and ultimately alleviate the burden on the public pension system. Detailed administrative data from the Federal Employment Agency allow to distinguish between employment and unemployment as well as disability pensions and retirement benefits claims. Using a Regression Kink design in a quasi-experimental framework, I show that the raised early retirement age had positive employment effects and negative effects on retirement benefits claims. The reform did not affect unemployment benefits or disability pensions claims. My results also show that some population groups are more sensitive to a reduction in retirement options and more likely to seek benefits from other government programs. In this respect, I find that workers in manufacturing sector respond to the raised early retirement age by claiming benefits from the disability insurance program designed to compensate for reduced earnings capacity due to severe health problems. The treatment heterogeneity analysis further suggests that high-wage workers are more likely to delay exits from employment, which is in line with incentives but might also indicate an increased inequality within the affected birth cohorts induced by the reform. Finally, women seem to rely on alternative sources of income such as retirement benefits for women, or spouse's or partner's income not observed in the data. All things considered, workers did not adjust to the increased early retirement age by substituting early retirement with other government programs but rather responded to the reform in line with the policy intent. At the same time, the findings point to heterogeneous behavioral responses across different population groups. This implies that raising the early retirement age is an effective policy tool to increase employment only among older people who have the real choice to delay employment exits. Therefore, reforms that raise statutory ages should ensure social support for workers only marginally attached to the labor market or not able to work longer due to potential health problems or other circumstances.

Personalpolitik in wissenschaftlichen Buchverlagen : Ergebnisse einer Umfrage (2011)

Martin, Albert ; Bartscher-Finzer, Susanne

Zusammenfassung Der vorliegende Bericht informiert über die Ergebnisse einer empirischen Studie zur Personalarbeit in wissenschaftlichen Buchverlagen. Als Grundlage der Erhebung dienten verschiedene theoretische Konzepte, die sich mit der Frage befassen, welche Grundmuster das Personalgeschehen von Unternehmen prägen. Das primäre Ziel unserer Studie bestand entsprechend darin, zu erkunden, inwieweit es gelingen kann – mit Hilfe einer Unternehmensbefragung – etwas über diese Grundmuster zu erfahren. Das Ergebnis stimmt zuversichtlich. Die theoretische Fundierung unserer Umfrage erwies sich als sehr tragfähig und empfiehlt sich für weiterführende und branchenübergreifende Vergleichsstudien. Leider war es uns an dieser Stelle noch nicht möglich, eine „großzahlige“ Erhebung durchzuführen, die Datenbasis, auf der unsere Ergebnisse beruhen, ist mit 12 Unternehmen denn auch einigermaßen schmal. Angesichts unserer Zielsetzung ist dies aber nur bedingt ein Mangel. Inhaltlich zeigt sich, dass die Personalpolitik der Verlage im Großen und Ganzen einem Schema folgt, das sich aus den branchentypischen Anforderungen ableitet. Andererseits findet man aber auch verlagsspezifische Akzentuierungen. In manchen Verlagen dominiert eher eine gemeinschaftliche Orientierung (in ihren jeweiligen Varianten), in anderen werden die leistungs- und managementorientierten Aspekte der Personalarbeit stärker betont.

Das Recht der Freileitung im Spannungsfeld planerischer, technischer und ökologischer Anforderungen (2019)

Lauer, Julian Justus

Die Energiepolitik in Deutschland hat in den letzten Jahren umfassende Veränderungen erfahren. In den Fokus rücken dabei immer mehr die erneuerbaren Energien. Deren Anteil an der gesamten Energieerzeugung wird in Zukunft weiter ansteigen. Hintergrund ist die Umsetzung der klimapolitischen Ziele der Bundesregierung: Im Energiekonzept für eine umweltschonende, zuverlässige und bezahlbare Energieversorgung von 2010 wird eine Reduktion der Treibhausgasemissionen um 40% bis zum Jahr 2020 und bis zum Jahr 2050 sogar um 80% gegenüber dem Stand von 1990 angestrebt. Neben dem Energiekonzept der Bundesregierung stellen das Reaktorunglück von Fukushima und die damit verbundene Energiewende 2011 eine wesentliche Zäsur für die Energiepolitik in Deutschland dar. Die Folge war ein beschleunigter Ausstieg aus der Kernenergie sowie die sofortige Abschaltung von acht Kernkraftwerken. Neben der Laufzeitverkürzung und Stilllegung von Atomkraftwerken wurde auch das aus mehreren neuen Gesetzen und Gesetzesänderungen bestehende Energiepaket verabschiedet. Dort wurde mit der Einführung der §§ 12a ff. Energiewirtschaftsgesetz erstmalig eine bundesweite Bedarfsplanung für den Bau von Höchstspannungsleitungen festgelegt. Zudem erfolgte mit der Einführung des Netzausbaubeschleunigungsgesetzes Übertragungsnetz (NABEG) erstmalig ein bundesweit gültiges Gesetz für die Planung von Vorhaben auf der Ebene der Höchstspannungsnetze. Die vorliegende Arbeit untersucht vor diesem Hintergrund die Frage, ob durch die neu geschaffenen Regelungen des NABEG für Höchstspannungsleitungen eine Beschleunigung innerhalb des Planungsverfahrens erreicht werden kann und ob die mit dem NABEG verfolgten Ziele umgesetzt worden sind. Dabei wird aufgezeigt, wie sich die Zielsetzungen des NABEG zu den denjenigen Zielen der im Rahmen der Abwägung der öffentlichen und privaten Belange zu beachtenden, sonstigen fachspezifischen Gesetzen verhalten. Der Beschleunigungsgedanke darf nicht dazu führen, dass umwelt-, immissionsrechtliche und sonstige fachgesetzliche Aspekte an Gewicht verlieren. Dabei werden auch mögliche Probleme der jetzigen Gesetzeslage beim Freileitungsausbau sowie weitere gesetzliche Möglichkeiten, die Beschleunigung des Netzausbaus zu erreichen, aufgezeigt.

Shifting Perspectives - towards a better understanding and a more effective promotion of women entrepreneurship in Sub-Saharan Africa (2019)

Wolf, Kathrin

In sub-Saharan Africa, women own or partly own one third of all businesses, thereby having a large potential to contribute to the economic development and societal well-being in this region. However, women-owned businesses tend to lag behind men-owned businesses in that they make lower profits, grow more slowly, and create fewer jobs. To identify reasons for this gap and effective means to promote women entrepreneurs, large parts of the entrepreneurship literature have compared male and female entrepreneurs with regard to individual characteristics, paying only limited attention to the underlying environmental conditions. This is problematic as women entrepreneurs operate under different conditions than men, with particularly pronounced differences in sub-Saharan Africa. Against this backdrop, the goal of this dissertation is to contribute to a more profound understanding of women entrepreneurship in sub-Saharan Africa and its promotion through training by examining critical context factors. Specifically, I analyze two context factors that influence women’s entrepreneurial performance and the success of training interventions: 1) women entrepreneurs’ husbands and 2) the entrepreneurship trainer. These analyses are embedded in considerations of the cultural, social, and economic conditions women entrepreneurs in sub-Saharan Africa are facing. In Chapter 2, I conduct a systematic literature review on spousal influence in entrepreneurship and identify six recurrent types of influence. Complementing the literature originating from Western settings, I develop propositions on how the sub-Saharan context affects husbands’ influence on women entrepreneurship in this region. In Chapter 3, I build on a cultural theory and an economic theory of the household to develop and empirically test a theoretical model of husbands’ constraining and supportive influences on women entrepreneurship in sub-Saharan Africa. The empirical results point to three distinct types of husbands that differ significantly in their impact on women entrepreneurs’ business success. In Chapter 4, I explore the influence of the trainer on the effectiveness of entrepreneurship training in sub-Saharan Africa by drawing on an unsuccessful training implementation. Qualitative analyses indicate that the use of adequate teaching methods is critical towards training success. Overall, this dissertation makes an important contribution towards a better understanding of women entrepreneurs in sub-Saharan Africa and their promotion by shifting the perspective from a purely individualist to a more contextualized view of women entrepreneurship.

Studies on national space legislation for the purpose of drafting china's space law (2019)

Yu, Huan

Space-related science and technologies affect our daily life dramatically. Many countries have already formulated national space regulations to regulate their space activities. China, as one space-faring country, has obtained impressive achievements in space science and technologies. In recent years, Chinese private space companies have sprung up quickly, which requires a stable and foreseeable legal framework to ensure development. However, compared to the other space powers, China is the only one that has not enacted any formal national space laws. Against the background of strengthening the rule of law in China, research on China´s domestic space legislation is valuable and significant. The purpose of this thesis is two-fold. First, to find the legal basis and necessity of national space legislation and to extract the basic content of the existing national space legislation, simultaneously, to identify the new developments in the content of other States´ legislative practices. Second, based on the study of national space legislation, to propose the essential content of China´s space legislation.

The influence of sustainability communication on the purchase decision : the case of specialist tour operators for educational tours (2019)

Tölkes, Christina

This thesis deals with the influence of sustainability communication on the purchase decision of sustainable tourism products involving German specialist tour operators. Sustainability communication is a challenge, because sustainable tourism is an abstract and vague concept which consumers find it difficult to grasp and about which they are sceptical, and the service characteristics of tourism products complicate the decision making stage, which is a high-involvement situation of uncertainty to which sustainable product attributes add complexity. As an introduction, an interdisciplinary theory discussion reveals knowledge gaps in terms of the value-belief-norm theory and the elaboration likelihood model (ELM). The first article, which is the first systematic literature review on the topic, reveals that there is a limited theoretical understanding of sustainability communication, a lack of practical understanding of how to design sustainability messages, and an inadequate set of methodologies for its research. It identifies knowledge gaps concerning: the holistic approach to sustainability communication; its role in the attitude-behaviour gap; an interdisciplinary theoretical understanding focusing on belief-based social psychological theories and theories of persuasion; qualitative methods; and experimental design. The second article investigates the role of sustainability communication in the attitude-behaviour gap, employing the value-belief-norm theory to explain how information is processed by special interest customers. Interview findings show that ineffective sustainability communication is the reason for the gap and that customers unintentionally booked sustainably. The study identifies eight groups of beliefs which explain the processing of sustainability attributes. Sustainability information is effective when it is value-congruent, that is, when customers perceive they can make a difference, they begin to ascribe a responsibility to themselves. The third article investigates how to design an effective sustainability message in tour operator advertising. Drawing on the ELM, the study shows that appeal type does not significantly influence persuasion but the topic presented is important. Cultural sustainability is the sustainability topic that is most persuasive for cultural tourists, while consumer prior knowledge and issue-involvement with the topic promote successful information processing. The thesis has contributed to a target-group specific understanding of effective sustainability product communication and contributes to knowledge in terms of theory, methodology, and practical solutions.

Sustainable opportunity identification and opportunity deviation : insights from a process perspective approach (2018)

Eller, Fokko Jelto

The process perspective provides a unifying framework that has substantially contributed to our understanding of entrepreneurship. However, much of the research up to now has neglected this process oriented conception of entrepreneurship. There is therefore a need for studies that take the inherent dynamic processes into account and analyze the underlying mechanisms when researching entrepreneurship. This dissertation aims to improve our understanding of the entrepreneurial process. Specifically, this dissertation focuses on new venture creation and the processes of sustainable opportunity identification and opportunity deviation. Chapter 1 provides a general introduction that highlights the theoretical contributions of this dissertation and gives an overview over the conducted studies. Chapter 2 argues for a process model of entrepreneurship that places entrepreneurs and their actions center stage. The model combines different perspectives and levels of analysis and provides an integrative framework for researching new venture creation. In chapter 3 we establish and test a theoretical model of sustainable opportunity identification. The chapter explains how younger generations identify sustainable opportunities. The findings indicate that sustainable opportunity identification is a process with two transitions from problem to solution identification and from solution identification to sustainable opportunity identification. These transitions are contingent on awareness of consequences and entrepreneurial attitude. Chapter 4 offers insights into how deviation from the original opportunity increases the performance of entrepreneurial teams. The findings indicate that entrepreneurial teams with a high level of error orientation set themselves higher goals when deviating from their original opportunity. Higher goals then lead to higher team performance. Chapter 5 summarizes the overall findings and outlines the general theoretical and practical implications. Each chapter thus contributes to the process perspective by focusing on how different phases of the entrepreneurial process unfold and develop over time. Thereby, this dissertation advances our understanding of entrepreneurship as a process.

Essays on corporate governance and financial reporting quality (2018)

Mutschmann, Martin

In this dissertation, I focus on the link between (internal) corporate governance structures and processes and firms financial reporting quality. Specifically, the dissertation aims to provide insights into the following general research question: What is the effect of different corporate governance stakeholders on the financial reporting quality of a firm? I provide insights into this question through three different articles. While Chapter 2 and 3 of this dissertation are concerned with company owners as one, albeit diverse, group of stakeholders, Chapter 4 focuses on managers and their ability to influence firm outcomes. The paper Do Family Firms Engage in Less Earnings Management? A Meta- Analysis, which is co-authored with Tim Hasso and Dominik Wagner, explores the relationship between family firm status and earnings management and synthesizes and explains previous research findings with the help of meta-analytic methods that are still uncommon in financial accounting research. We find a negative relationship between family firms and earnings management on average across 37 primary studies (and 305 effect sizes in total). Furthermore, we show that the considerable variation in size and direction of primary effect sizes can be explained by researchers choice of study design, earnings management proxy and different institutional settings. The paper Do Institutional Owners Deter Earnings Management? A Meta- Analysis, which is co-authored with Tim Hasso, explores institutional owners as a different set of shareholders and their impact on financial reporting quality. The study enables us to compare the results against the backdrop of the previous chapter and to see different rationales that managers in institutionally-owned companies might have to engage in earnings management. Here, we study 511 effect sizes from a total of 87 primary studies and find that the average effect is slightly negative, meaning institutional owners on average can get more transparent earnings figures from the companies they invest in. Similar to the work we did on family firms, we find considerable heterogeneity between results from primary studies. Specifically, our multivariate meta-regression models can explain 26 percent of the variability in effect sizes, mainly attributable to study design choices, such as how scholars measure the relevant constructs of ownership and earnings management. Conversely, this also indicates that across the 87 primary studies looking at the link between institutional ownership and earnings management, 74 percent of heterogeneity in effect sizes is still not explained. The single-author paper The Fish Rots From the Head Down: Managerial Personality and Financial Accounting Manipulation is concerned with managers - the second main stakeholder in corporate governance - and how managerial personality drives the propensity to engage in fraudulent accounting activities. I use a primary sample of 956 professionals, who work in accounting and finance departments, and ask them to rate their immediate superior on dark triad personality traits, as well as common actions taken by management to obscure and manipulate earnings figures. I find that managers with high ratings for dark triad personality traits engage to a greater extent in fraudulent accounting practices, than managers scoring low on the dark triad scale. Moreover, I can show that traditional risk management mechanisms, like internal audit departments, are only partially effective. Specifically, I find that only internal audit departments that are fully staffed by external personnel can curb the adverse effect of dark triad managers on financial reporting quality. This suggests that managers with dark personalities can take advantage of mixed or entirely in-house internal audit departments. Overall, this dissertation contributes significantly to both literature streams of corporate governance and financial reporting quality. My work can explain a significant degree of heterogeneity in previous findings on the link between different kinds of ownership and earnings management. Further, it stresses that the considerable variation in current findings is not mainly attributable to cross-country differences, as previously suggested, but in no small part attributable to study design features. Both meta-analysis papers are among the first articles that apply advanced metaregression methods in the financial accounting literature. Thus, contrary to previous methods of research synthesis meta-analyses are uniquely able to draw systematic, quantitative and replicate conclusions from a body of academic research. Especially for large, mature literature strands taking stock of all findings on a specific relationship is valuable, as research rarely progresses one paper at a time. Condensing and differentiating cumulative research via meta-analysis is thus a valuable contribution to the field and can be a basis for further theory development and improvements in empirical study designs. Finally, I can provide additional evidence on current research linking executive personality traits and financial reporting practices. Asking practitioners directly about their assessment of managerial personality and the frequency of specific fraudulent actions helped to show the critical role of executive personality and complements recent archival and experimental findings. The survey design also enables me to study so far undetected fraud, which is almost impossible to examine with experimental or archival data and thus a significant contribution to existing literature. Finding links between managerial personality, internal controls and reporting quality contributes to the literature further, as it shows previously unhypothesized relationships that can serve as a basis for future research on the effectiveness of internal audit functions in preventing fraud given different managerial personality traits.

Mindsets and the effectiveness of negotiation training (2018)

Ade, Valentin

In this cumulative thesis, I present four manuscripts and two appendixes. In the manuscripts I discuss mindsets and their relation to the effectiveness of negotiation training. My general claim is that mindsets promise to be relevant for training effectiveness. Still, more research needs to be done and my co-authors of chapter 3 and I present the Scale for the Integrative Mindset of Negotiators (SIM) that can be used for some of that research. In the appendixes, I present two negotiation training exercises. The first addresses an international refugee policy summit and the second a negotiation over the sale of a large solar pv park in Thailand.

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