Open Access

In this dissertation the relation between time headway in car following and the subjective experience of a driver was researched. Three experiments were conducted in a driving simulator. Time headways in a range of 0.5 to 4.0 seconds were investigated at 50km/h, 100km/h, and 150km/h under varied visibility conditions and at differing levels of driver control over the car. The main research questions addressed the possible existence of a threshold effect for the subjective experience of time headways and the influence of vehicle speed, forward visibility, and vehicle control on the position of time headway thresholds. Furthermore, the validity of zero-risk driver behavior models was investigated. Results suggest that a threshold exists for the subjective experience of time headways in car following. This implies that the subjective experience of time headways stays constant for a range of time headways above a critical threshold. The subjective experience of a driver is only influenced by time headway once this critical time headway threshold is passed. Speed does not influence preferred time headway distances in self- and assisted-driving, i.e. time headway thresholds are constant for different speeds. However, in completely automated driving preferred time headways are influenced by vehicle speed. For higher speeds preferred time headways decrease. A reduction of forward visibility leads to a shift in preferred time headways towards larger time headways. Results of this dissertation give credence to zero-risk models of driver behavior.

Micro- and small enterprises are of great importance for the economic growth in developing countries, as they contribute to employment creation and innovation. In light of their economic relevance, several approaches to support micro- and small enterprises have emerged, including building human capital through business trainings. However, the effects of existing business trainings on entrepreneurial success have so far been limited. One promising alternative training approach that has emerged in the last years is personal initiative training, which teaches self-starting, future-oriented, and persistent entrepreneurial behavior. This dissertation helps to improve the understanding of personal initiative training by shedding light on the mechanisms through which it affects business success, on supporting factors, and on its long-term impacts. Chapter 1 provides an overview on the topic of personal initiative training for entrepreneurs in developing countries. Chapter 2 introduces personal initiative training and other proactive behavior trainings in various contexts of work, including entrepreneurship. The chapter presents action regulation theory and the theory on personal initiative as the theoretical foundation of the training. In addition, the chapter provides insights into training and evaluation methods and makes recommendations for the successful implementation of personal initiative training. Chapter 3 offers a first answer to the question how personal initiative after training can be maintained over time. The chapter introduces training participants´ need for cognition as beneficial factor for post-training personal initiative maintenance. Chapter 4 explains how action regulation trainings like personal initiative training contribute to poverty reduction in developing countries by supporting entrepreneurial success. Chapter 5 enlarges upon the topic of personal initiative training for entrepreneurial success in developing countries. The chapter focuses on how personal initiative training supports female entrepreneurs in developing countries by helping them to overcome the uncertainty involved in entrepreneurial actions. Chapter 6 summarizes the overall findings and illustrates the theoretical and practical implications that result from this dissertation. In sum, this dissertation makes a contribution to the better understanding of personal initiative training and its effects on entrepreneurship in developing countries and thereby helps to create effective interventions to combat poverty in developing countries.

In 2013, the European Commission adopted the so called ´Entrepreneurship 2020 Action Plan´ to ease the creation of new ventures and to support the takeover of existing firms. The goal is to create a supportive environment for entrepreneurs to thrive and grow (European Commission 2013). This shows that the European Union puts its efforts to support small firms as they are seen as means for Europe´s sustainable economic growth. However, the successful processes of growth and investment are complex and depend on different determinants. The present thesis focuses on the firm level and analyzes in three independent articles: how small firms invest over time, how new ventures grow and which variables influence growth, how small firms grow after business takeover and which variables influence growth. The framework that connects these articles forms the content-related focus on the early stage of development of small firms and the methodological and analytical approaches that comply with up-to-date and adequate statistical analysis techniques. Supported by an extensive dataset, which is the foundation of all three articles, it is possible to investigate empirically different open research questions using bivariate and multivariate analysis techniques. Thus, this thesis also serves the research needs for more multivariate analyses for small firms, for which so far mainly cross-sectional studies have been conducted.

In this work, I contribute to a social constructionist research agenda by investigating how managers/consultants (practitioners) of different ranks are engaged in patterns of behavior (practices) in socially situated contexts (practice) attempting to shape preferred shared interpretations of reality to achieve their goals. Following this line of inquiry, the work aims at (1) advancing our understanding of the role of practitioners in shaping managerial realities and (2) investigating how practitioners actually shape managerial realities, particularly focusing on ´reality-shaping´ practices and their content. The dissertation comprises a set of four complementary articles investigating these research questions empirically based on in-depth, empirical case studies and theoretically within various managerial contexts (client-consultant relationship, CEO post-succession strategic change process, evolutionary initiative development) and considering different actor perspectives (top managers, middle managers, consultants and clients). Resulting from this variety, the articles rely on and contribute to different, at times distant, research fields and therewith scholarly discussions. However, the literature on sensemaking and sensegiving offers a suitable overarching theoretical frame which I use in this work to synthesize the key contributions of the four articles.