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A functional central limit theorem for recursive residuals and applications in asymptotic statistics
(2022)
We study partial sums of recursive residuals, define a recursive residual partial sum process and prove that this process converges weakly against Brownian motion. For not normally distributed errors, the limit process has been known only for time series samples under assumptions that are difficult to verify, or in the case of triangular schemes of design points only under strong assumptions on the regression functions. For the first time, we determine the limit process for triangular schemes without the restrictive assumption of normally distributed errors and under very mild assumptions on the regression functions (they have to be left continuous, of bounded variation and linearly independent with respect to the L2 norm) that are of great benefit for practical applications. Crucial for the proof are Donsker's invariance principle for triangular schemes, a technique to factorize simultaneously a family of functions and Rubin's famous continuous mapping theorem. Our approach, based on Rubin's theorem, further allows us to compute the distribution of the limit process under local alternatives. With the help of these asymptotic results we are then able to define and study asymptotic tests and we give an example of an asymptotically uniformly most powerful test.
We also give an introduction to the theory of weak convergence of finite measures, and present these classical results in a more general form than usual. We consider measures on perfectly normal spaces instead of metric spaces, and we consider filters of measures instead of sequences of measures.
This dissertation comprises three empirical studies on corporate social responsibility (CSR). The first study examines how an exogenous increase in agency problems affects CSR investment decisions. The second study examines whether the value relevance of CSR reporting is affected by customer profile differences. The third study examines how national culture shapes several fundamental corporate decisions determining the credibility of CSR reports. Collectively, the three studies provide novel and holistic evidence on why managers pursue CSR.
1. Steindl, T., Hellmann, A. and Goettsche M. 2017. Building a social empire? Managerial preferences, shareholder litigation, and corporate social responsibility. Working Paper.
2. Goettsche, M., Steindl T. and Gietl S. 2016. Do customers affect the value relevance of corporate social responsibility reporting? Empirical evidence on stakeholder interdependence. Business Strategy and the Environment 25(3): 149-164.
3. Steindl, T. 2017. Cultural rule orientation, legal institutions, and the credibility of corporate social responsibility reports. Working Paper.
This thesis develops methodological approaches to extend the service spectrum of price comparison websites for electronic consumer goods with respect to the determination of the optimal purchase time point. The central decision criterion of price comparison sites’ customers is the (expected) minimum price.
This paper therefore focuses on the prediction of minimum prices and therefrom derived events and answers three questions that set the stage for extending services of price comparison sites:
1. How long do is the expected waiting time to buy our desired product for a set budget or desired price?
2. When should a customer buy so that s/he pays the lowest price within a short, predefined decision horizon?
3. How can a price comparison site make price predictions for a large, heterogeneous set of products over different horizons, and what are the best methods for doing so?
The database used for the analysis results from the specific requirements of the study context. While the first two papers focus on a subset of electronic consumer goods - smartphones - to demonstrate the application of the developed methodology, the third paper addresses the challenges of price prediction for the heterogeneous product landscape on price comparison sites and therefore includes multiple product categories in the analysis.
This study comprises three individual contributions to the research focus on pricing of auditing services. Using German and European data sets, the empirical investigation examines, among other things, how different dimensions of size, possible interactions from a so-called Big 4 premium or fee cutting behavior, as well as different financial risk factors affect the level of auditing services.
The study 'Size effects and audit pricing: Evidence from Germany' shows, among other things, that of those auditors who also provide consulting services for their clients, only Big 4 auditors achieve higher fees for auditing services. Furthermore, the results of the study suggest that the Big 4 premium shown in previous studies for the German market is strongly influenced by a market leader premium. Taking into account the high relevance of company size as a factor in the pricing of audit services, the study also concludes that company size should rather be represented by non-financial variables such as the natural logarithm of the number of employees in order to exclude any interdependencies with other financial variables.
The study entitled 'The Big 4 premium: Does it survive an auditor change? Evidence from Europe' presents new findings on the impact of auditor changes on audit fees, with a special focus on a possible Big 4 premium. This combines the previous research on the Big 4 premium and fee cutting. Matching analyses are used to compare the audit fees of companies that switch to a Big 4 auditor with those companies that switch to a non-Big 4 auditor. As a result, a Big 4 premium can only be shown for those companies that do not change auditors. In the case of a change of auditor, the results show that Big 4 auditors are willing to give up this bonus or even accept a discount on non-Big 4 auditors. This discount usually persists in the first few years. Accordingly, the assumption is that Big 4 auditors are pursuing a "foot-in-the-door" strategy to win new clients. Based on these results, the existence of a Big 4 premium is strongly dependent on the decision of the respective company to change auditors.
The study 'Variation of financial risk over time and the impact on audit pricing' focuses on the consideration of financial risk factors and their development over time. The key assumption of the study is that continuity of relevant financial ratios reduces the risk position of the auditor and should be positively reflected in the audit fees. For companies that do not change auditors, the results show an influence of increased volatility of financial ratios on the level of audit fees. This leads to the assumption that in case of increased volatility in the financial ratios, companies could deliberately not change the auditor in order to send a sign of stability to third parties and, if necessary, accept a premium on the existing auditor's fees. In the case of a change of auditor, however, new auditors could waive a corresponding premium in order to win new clients.
In many countries today, a rising life expectancy and the associated demographic shift, coupled with the advancements of modern medicine, has fueled an ever-increasing cost pressure on healthcare systems. A driving factor for these rising costs can be seen in inpatient stays in hospitals that in many cases are connected to cost-intensive treatments. A central concern of any hospital management in such an environment is therefore to understand how to make the best possible use of available resources. A decisive factor in this regard is the management of bed capacities.
The present cumulative dissertation comprises four contributions, which address
open research questions in the field of strategic, tactical and operative bed planning:
1 Walther, M., 2020. Strategical, tactical, and operational aspects of bed
planning problems in hospital environments. Submission planned to
Social Science Research Network (SSRN)
2 Hübner, A., Kuhn, H., Walther, M., 2018. Combining clinical departments
and wards in maximum-care hospitals. OR Spectrum 40, 679-709
3 Schäfer, F., Walther, M., Hübner, A., Kuhn, H., 2019. Operational
patient-bed assignment problem in large hospital settings including overflow
and uncertainty management. Flexible Services and Manufacturing
Journal 31, 1012–1041
4 Schäfer, F., Walther, M., Hübner, A., Grimm, D., 2020. Machine learning
and pilot method: tackling uncertainty in the operational patient-bed
assignment problem. Submitted to OR Spectrum on 13 February 2020
The first contribution sets out to provide an overview over the different hierarchical planning levels on which bed planning problems may be addressed. It should be noted in this context that several different aspects may be combined under the collective term “bed planning”. These may be delimited in terms of their scope and their planning horizon. A frequently used taxonomy in this context is the hierarchical subdivision of typical problems in health care into strategical, tactical and operational levels as provided by Hulshof et al. (2012). In the context of bed planning, a typical strategical problem is how to combine departments and wards to obtain benefits from pooled ward capacity. On a tactical level, an exemplary problem setting related to bed planning can be seen in devising master surgery schedules that optimize downstream bed occupancy levels as patients returning from surgery will require a bed for post-surgical recovery and monitoring. Finally,
on an operational level, patient-bed allocations need to be optimized while taking the objectives and constraints of patients and medical staff alike into account.
To start, the second contribution deals with the strategical problem of combining departments into groups and assigning pooled ward capacity to these groups with the goal of balancing bed occupancy levels within a hospital. Specifically, one of the underlying goals is to minimize the amount of beds required to meet a predetermined service level. However, merging ward capacities with the aim of simultaneously accommodating patients from different medical departments increases the complexity of organizing and ensuring proper care for these patients. This leads to so-called pooling costs. To tackle this problem, a modeling and solution approach is developed which is based on a generalized partitioning problem and is solved by integer
linear programming (ILP). This enables hospital management to determine the cost-optimal combination of all departments and wards in a hospital, while ensuring that predetermined thresholds with regard to maximum
walking distances for doctors and patients are adhered to.
Once pooled ward capacities are established, the solution space for allocating incoming patients to beds is greatly increased and the underlying allocation problem quickly becomes too complex to be handled without computational support. In this regard the third contribution ties in with the second contribution in that it deals with optimizing the operational patient-bed allocation problem. In order to enable optimal allocation of patients to beds, it is important to identify and take into account the individual needs and
limitations of the three main stakeholders involved, namely patients, doctors, and nursing staff. All of these stakeholders exhibit different and sometimes contradicting objectives and constraints, such that a trade-off has to be made that maximizes the overall utility for the hospital. In addition, the complexity of the problem is increased by the high volatility and uncertainty regarding patient arrivals, types of illnesses, and the resulting remaining lengths of stay of newly arriving patients. In order to address this situation,
a mathematical model and solution approach for the patient-bed allocation problem is developed that is designed to generate solutions for large, real-life operative planning situations. In addition to being able to deal with overflow situations, this solution approach further takes different patient types into account, for example by anticipating emergency patient arrivals.
Finally, the fourth contribution builds on the third contribution in that the modeling and solution approach to allocate patients to beds is extended by several aspects. As mentioned above, hospitals have to deal with uncertainty regarding the actual demand for beds. Here, the fourth contribution improves the anticipation of emergency patients by using machine learning. Specifically, weather data, seasons, important local and regional events, and current and historical occupancy rates are combined to better anticipate emergency inpatient arrivals. In addition, a hyper-heuristic approach is developed based on the pilot method defined by Voß et al. (2005). By combining the improved anticipation of emergency patients with this hyperheuristic approach significant improvements can be achieved compared to the solution approach presented in the third contribution.
Biogeomorphology from space
(2021)
In the arid and semi-arid climate of Central Asia, the endorheic rivers and their ecosystems play a crucial role as regional hotspots of biodiversity and for the provision of ecosystem services for local people. The Naryn River in Kyrgyzstan as the object of interest of this thesis is one of these rivers. On a flow length of more than 600 km, it is still in a widely natural condition making it an interesting study object in a world where most large rivers are distorted by anthropogenic activities. Despite this relevance, no comprehensive scientific studies are available about the Naryn River except water resource related research. In particular, large scale information about the structure and functioning of the Naryn River system from an interdisciplinary perspective is missing. Against this background, this thesis aims to fill the research gap and deliver up-to-date information about the Naryn River corridor with a special focus on biogeomorphology, i.e. the dynamic interaction between hydromorphology and vegetation. First, this thesis delivers the necessary background information about the Naryn River corridor including a general overview, an assessment of ecosystem services, a field based overview of the structure of the riparian ecosystems and an in-depth analysis of hydrology. Basing upon this background, remote sensing methods adapted to the data-scarce environment of Central Asia are used to derive various parameters of the structure of the Naryn River on the scale from reaches to the entire river corridor. Then, the large scale biogeomorphological structures and dynamics are assessed based on dense time series of multispectral satellite imagery. From the results, it becomes obvious that the structure of the corridor of the Naryn River is heterogeneous and mainly controlled by geological contraints. Only in a laterally unconfined segment, dynamic braided river reaches can form. In these reaches, the majority of biogeomorphological interactions take place. The outcome of this thesis is on the one hand the provision of large scale and up-to-date information about the structure and functioning of the Naryn River corridor as a basis for further research or decision making. On the other hand, this thesis presents innovative remote sensing methods for large scale characterization of river corridors. In particular, an approach for the characterization of dynamic processes of biogeomorphological interactions on a large scale is developed based on time series analysis of satellite imagery. This approach can complement biogeomorphological research on smaller spatial scales by delivering spatially and temporally continuous information for entire river corridors. This has the potential to obtain new insights of the processes and emergence of structure in river systems across multiple scales.
This cumulative dissertation deals with a systematic review of experimental service research over four decades and the cause-and-effect relationships within social media recovery. In total, the dissertation comprises three articles:
1) Albrecht, K. (2016): Understanding the Effects of the Presence of Others in the Service Environment – A Literature Review, in: Journal of Business Market Management, Vol. 9, No. 1, p. 541-563 (VHB-JQ3:D).
2) Hogreve, J. / Bilstein, N. / Hoerner, K. (2018): Service Recovery on Stage: Effects of Social Media Recovery on Virtually Present Others, revise and resubmit (2nd round) to Journal of Service Research (VHB-JQ3:A) in July 2018.
3) Hogreve, J. / Matta, S. / Hoerner, K. (2018): Cause and Effect: A Systematic Review of Four Decades of Experiments in Service Research, to be submitted to the Journal of Service Research (VHB-JQ3:A).
The first article is a literature review of existing research on the effects of the presence of others in the service environment. Through a systematic literature analysis three context factors could be identified, which significantly influence the interaction between customers in the service environment (online/offline). The second article examines the effects of a specific form of indirect customer interaction by means of several quantitative studies: The effects of customer complaints and subsequent service recovery in social media on virtually present others. The third article presents the current state of experimental service research over a period of four decades by means of a systematic literature analysis and identifies research gaps that should be addressed by future research.
The essays of the cumulative dissertation are concerned with the distribution in retailing with multi-compartment vehicles.
An effective distribution planning is a central aspect for the success of retailers. Due to a highly competitive market, retailers are forced to constantly optimize processes along the supply chain to satisfy the given requirements. On the one hand, customers expect the constant availability of various products while asking for high quality. On the other, an ever increasing pressure on prices exists. The involved logistic processes therefore need to be highly efficient to fulfil the given requirements. An important part plays thereby the distribution of goods to stores, where consumers are supplied. Here, multi-compartment vehicles offer a variety of new possibilities for distribution. The core attribute of multi-compartment vehicles is the simultaneous delivery of different temperature zones with the same vehicle. Besides the new options that therefore open up for distribution, further processes and costs incurred by the use of multi-compartment vehicles need to be taken into account.
The first essay presents the basic attributes of multi-compartment vehicles as well as the differences to processes with single-compartment vehicles. The distribution with both single- and multi-compartment vehicles is illustrated and the differences are discussed. Further, the essay discusses current literature for the distribution with multi-compartment vehicles in retailing. Based on these findings, a formal model for the distribution with multi-compartment vehicles is presented in the second essay. The model considers cost and process differences, especially for loading and unloading actions. The use of multi-compartment vehicles is analysed and saving potentials revealed, using the model and a tailor-made solution approach. The remaining essays (essays 3, 4 and 5) further extend the introduced model to consider additional aspects relevant in practice. More precisely, the third essay considers the optimal fleet mix if both single- and multi-compartment vehicles are available for distribution. The fourth essay identifies loading restrictions if multi-compartment vehicles are used and presents an innovative solution approach to address the arising problem and which enables a distribution planning without loading and unloading problems. Finally, the concluding essay (essay 5) extends the discussed planning problem for multiple periods. In particular, it examines the impact of consistent deliveries for all considered product segments across the complete planning horizon.
This cumulative dissertation aims to provide novel and holistic ideas on how companies can solve different challenges in the implementation of responsible business conduct (RBC).
The dissertation entails three individual scientific papers:
1. Baier, C., Göttsche, M., Hellmann, A., and Schiemann, F. (2021), “Too good to be true: Influencing credibility perceptions with signaling reference explicitness and assurance depth”, published online in the Journal of Business Ethics (VHB-JQ3: B), doi: 10.1007/s10551-020-04719-7.
2. Baier, C., Beckmann, M., and Heidingsfelder, J. (2020), “Hidden allies for value chain responsibility? A system theory perspective on aligning sustainable supply chain management and trade compliance”, published in the International Journal of Physical Distribution & Logistics Management (VHB-JQ3: B), Vol. 50 No. 4, pp. 439-456, doi: 10.1108/IJPDLM-02-2019-0037.
3. Baier, C. (2020), “Strengere Sorgfaltspflichten für verantwortungsvolle Lieferketten?”, published in DER BETRIEB (VHB-JQ3: D), Vol. 35, pp. 1801-1805.
The three papers of this dissertation concentrate on specific facets of RBC and aim to find new insights and solutions for different challenges in the implementation of RBC. The first paper investigates ethical sustainability reporting and assurance practices. The second paper emphasizes that corporations are responsible to manage both the upstream and downstream sustainability impacts on the value chain and thus concentrates on the RBC aspect of value chain responsibility. The third paper focuses on the concept of supply chain due diligence to identify, prevent, mitigate, and account for adverse human rights and environmental impacts as an elementary part of RBC.
The overall aim of this cumulative dissertation is to contribute to a better understanding of both antecedents of the usage of automated mobility offerings and outcomes that individual consumers experience from such usage. The dissertation contains three distinct papers:
Paper 1: Janotta, F. (2022), “Making emergent technologies more tangible - Effects of presentation form on user perceptions in the context of automated mobility”
Paper 2: Janotta, F. & Hogreve, J. (2022), “Ready for take-off? The dual role of affective and cognitive evaluations in the adoption of Urban Air Mobility services”
Paper 3: Janotta, F.; Hogreve, J.; Gustafsson, A. & Lervik-Olsen, L. (2022), “Will automated mobility contribute to consumer well-being? The role of mindfulness interventions in the context of automated driving”
Each paper addresses a specific prevailing research gap in the literature related to automated mobility offerings, focusing on different use cases of automated mobility. Paper 1 investigates the effects of different presentation forms of automated driving on consumers’ perceptions, thereby addressing the challenge of effectively visualizing emergent automated technologies and making them more tangible to respondents in the context of empirical research, thus providing a methodological basis for the further investigation. Paper 2 investigates antecedents of consumers’ adoption intentions of autonomous passenger drones, specifically focusing on the dual role of affective and cognitive considerations in the formation of usage intentions. Paper 3 investigates outcomes of consumers’ usage of automated mobility offerings, focusing on the use case of automated driving and its effects on individual well-being of consumers.