Open Access

Leadership development is often approached as an individual process focused on traits, competencies, and formal learning interventions. This dissertation reconceptualizes leadership development as a socially embedded, observational, and contextually shaped process, termed Observational Leadership Development. With particular attention to management consultancies as dynamic professional environments characterized by frequent exposure to diverse leader role models, the dissertation draws on social learning theory, identity theory, and qualitative analysis to examine how individuals learn leadership through observing, interpreting, and selectively integrating the behaviors, values, and practices of multiple leader role models. Across three studies, it develops a conceptual understanding of leader role models, identifies key characteristics, and shows how career ambitions, organizational context, and career tenure influence role model selection and leadership learning. It further identifies three reflective processing modes — situational adaptation, selective integration, and contrastive delineation — that explain how observed leadership experiences are translated into leader identity formation. Building on these insights, the dissertation proposes a Leadership Learning Cycle that captures the recursive interplay of observation, reflection, identity work, and contextual influence in leadership development.

This dissertation examines the role of tax policy in enhancing a country’s attractiveness as a business location and promoting corporate investment, innovation, and economic growth. Against the backdrop of declining economic growth in Germany and increasing structural challenges, the study investigates whether tax incentives and efficient tax frameworks can stimulate private investment and strengthen international competitiveness. The dissertation consists of three empirical studies. Chapter 1 analyzes the effects of tax incentives for automation using a quasi-natural experiment based on a reduction in South Koreas automation tax credit and a difference-in-differences approach combining robot and firm-level data. Chapter 2 evaluates the effectiveness of indirect tax incentives for research and development (R&D), focusing on Germany’s research allowance and drawing on both existing empirical evidence and innovation data. Chapter 3 examines the economic consequences of tax complexity using an international sample of publicly listed firms and a two-way fixed effects regression framework. The findings show that tax incentives significantly influence corporate investment decisions. Automation tax incentives increase investment in automation but may also encourage inefficient over investment, while their reduction leads to lower automation investment and higher employment. R&D tax incentives stimulate research expenditure, innovation output, productivity, and R&D-related employment. At the same time, the results demonstrate that tax complexity imposes substantial economic costs by reducing firm value, increasing compliance burdens, and weakening the effectiveness of tax incentives. Overall, the dissertation highlights that tax policy can contribute to economic growth and location attractiveness when it simultaneously provides targeted investment incentives and maintains a transparent and efficient tax system. The findings offer important implications for the design of tax policy aimed at fostering investment, innovation, and long-term competitiveness.

Understanding redistribution preferences in diverse societies is central to current debates on the European welfare state, yet empirical evidence remains incomplete. This dissertation contributes new evidence towards closing this gap. All three papers build on the large-scale comparative dataset of the ESS. In the first two papers OECD and Eurostat statistics are used to measure immigration. In addition asylum inflows are tracked by means of data from the European Observation Network for Territorial Development and Cohesion (ESPON) in the second paper. In the third paper detailed household income information from the European Union Statistics on Income and Living Conditions (EU-SILC) is used to enable a microsimulation of transfers required to eliminate poverty under a EU-wide Social Benefit Scheme. Combined, these data allow for both the replication of earlier findings (as in the first paper) and the development of new identification strategies (as in the second and third papers). Across the three studies, three consistent findings emerge. First, material self-interest remains stable over the three research papers: higher income is in general associated with less support for redistribution. Second, the Progressive’s Dilemma is not robust across time or space as the effect of heterogeneity is context-sensitive. Thus, short-run refugee inflows do not automatically undermine solidarity. In contrast, support for redistribution declines in regions less exposed to refugee inflows after 2015, while remaining largely unchanged in regions hosting large numbers of refugees, a robust pattern that runs counter to the Progressive’s Dilemma hypothesis. Third, when redistribution is scaled to the European level, support depends crucially on incidence: individuals in net payer countries, and those who fear lower domestic benefits from EU social policies, are less supportive. Generally, these results suggest that while self-interest is a stable driver, diversity and ethnic heterogeneity are far more complex and indeed context-dependent. This dissertation contributes to the literature in three ways. First, it demonstrates the importance of replication and extension tests that vary along temporal, spatial, and measurement dimensions. The current literature should consider how its empirical basis evolves over time and space. Also, the second paper provides new causal evidence on how asylum inflows shape redistribution preferences by exploiting the so-called “asylum crisis” as a natural experiment that generated exogenous variation in regional ethnic heterogeneity rates. Third, it highlights the role of fiscal incidence in shaping support for cross-national redistribution schemes. Taken together, these contributions advance our understanding of how solidarity, self-interest, and ethnic heterogeneity interact in modern European welfare states. The first paper features an extension test of David Rueda’s (2018) study “Food Comes First, Then Morals: Redistribution Preferences, Parochial Altruism, and Immigration in Western Europe”. It analyzes how household size, an extended time horizon, and the inclusion of Eastern European countries affect the original findings. Building on these results, the second essay—joint work with Jakob Sch¨auble and J¨org Althammer—exploits the European refugee crisis of 2015/16 as a quasi-natural experiment to study the causal effects of increased ethnic heterogeneity on natives’ willingness to support welfare programs. The third essay analyzes how support for a European-wide minimum income scheme differs between individuals living in net payer versus net recipient countries. All essays are based on stand-alone research papers that are included below in their current form.

This dissertation explores key challenges and innovations in contemporary asset management through three self-contained empirical essays. Each paper examines a distinct but interrelated topic in portfolio construction, contributing to a more resilient and practically viable approach to investing. Paper 1: The Performance of Risk-Based Asset Allocation in Downward Markets – An Empirical Examination The first paper investigates the effectiveness of risk-based portfolio strategies – such as minimum variance, equal risk contribution, and risk parity – during periods of market stress. Motivated by the shortcomings of return-optimized models in crisis periods, the paper conducts an extensive backtest using a multi-asset dataset across several downturns. It finds that risk-based strategies consistently offer superior downside protection and more stable performance compared to traditional approaches. These results underscore the robustness of risk-focused allocations when facing uncertain or volatile markets. Paper 2: A Performance “Horse Race”: Does Anything Beat the 1/N Portfolio? The second paper revisits the enduring puzzle of the 1/N (equal-weighted) portfolio's performance. Despite its simplicity, previous research has shown it often rivals or outperforms optimized strategies. Using an expanded dataset and robust methodology, this paper compares a wide range of portfolio construction techniques – including mean-variance optimization and shrinkage methods – against the 1/N benchmark. The findings reaffirm the strong performance of the naïve strategy, particularly when estimation error and real-world frictions are considered. While some optimized models perform better in specific contexts, none dominate consistently. Paper 3: Index Tracking in Crisis Periods – An Empirical Investigation of the German DAX Index The third paper shifts focus to passive investment strategies, specifically the accuracy and stability of index tracking during market crises. Using the German DAX as a case study, the paper compares multiple tracking approaches – such as constrained regression and relative optimization – under both normal and crisis conditions. Results reveal that tracking performance deteriorates notably in turbulent markets, with simpler, constraint-based methods offering more consistent tracking accuracy. This highlights the limitations of passive strategies under stress and points to the need for more adaptive frameworks.

This cumulative dissertation contributes to the research stream Future of Work and focuses on alternative workplace arrangements, especially when employees rely on information and communication technologies to communicate virtual feedback. More specifically, this dissertation addresses (1) the various conceptualizations and terminologies which researchers use for analyzing alternative work arrangements since the 1970s, (2) the multidimensional nature of virtual feedback, its effects on an individual and team level as well as the underlying cognitive processes when receiving virtual feedback, and (3) the effect of feedback on performance improvement when teams receive in-person or virtual feedback. This results in the following three manuscripts: Manuscript 1: Schäfer, B., Koloch, L., Storai, D., Gunkel, M., & Kraus, S. (2023). Alternative workplace arrangements: Tearing down the walls of a conceptual labyrinth. Journal of Innovation & Knowledge, Vol. 8, 100352. Manuscript 2: Koloch, L., Goldmann, P., Schäfer, B., & Ringlstetter, M. (2023). Feedbacking research on virtual feedback: A literature review. Manuscript 3: Koloch, L. (2023). Is virtual feedback less effective than in-person feedback for improving team performance? An experimental study.