TY - THES A1 - Norberto Sales, Juliano Efson T1 - An Explainable Semantic Parser for End-User Development N2 - Programming is a key skill in a world where businesses are driven by digital transformations. Although many of the programming demand can be addressed by a simple set of instructions composing libraries and services available in the web, non-technical professionals, such as domain experts and analysts, are still unable to construct their own programs due to the intrinsic complexity of coding. Among other types of end-user development, natural language programming has emerged to allow users to program without the formalism of traditional programming languages, where a tailored semantic parser can translate a natural language utterance to a formal command representation able to be processed by a computational machine. Currently, semantic parsers are typically built on the top of a learning method that defines its behaviours based on the patterns behind a large training data, whose production frequently are costly and time-consuming. Our research is devoted to study and propose a semantic parser for natural language commands targeting a scenario with low availability of training data. Our proposed semantic parser follows a multi-component architecture, composed of a specialised shallow parser that associates natural language commands to predicate-argument structures, integrated to a distributional ranking model that matches the command to a function signature available from an API knowledge base. Systems developed with statistical learning models and complex linguistics resources, as the proposed semantic parser, do not provide natively an easy way to associate a single feature from the input data to the impact in system behaviour. In this scenario, end-user explanations for intelligent systems has become a strong requirement to increase user confidence and system literacy. Thus, our research designed an explanation model for the proposed semantic parser that fits the heterogeneity of its multi-component architecture. The explanation model explores a hierarchical representation in an increasing degree of technical depth, providing higher-level explanations in the initial layers, going gradually to those that demand technical knowledge, applying different explanation strategies to better express the approach behind each component. With the support of a user-centred experiment, we compared the utility of different types of explanations and the impact of background knowledge in their preferences. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10718 ER - TY - THES A1 - Koçer, Volkan T1 - Three Essays on Global and Local Brands N2 - In three essays, this dissertation examines the past, present and future of branding in an international context, contributing to the research area of global/local brands, while also offering managers valuable insights for their branding strategies. The first essay provides scholars and practitioners a detailed state of the art of global/local brand research and proposes promising angles for future research, especially considering major challenges for our societies. The second essay incorporates the segment of cosmopolitan consumers into perceived brand globalness/localness research. Theoretically grounded in the concepts of social identity theory and complexity, the essay builds on perceived brand globalness/localness to analyze how cosmopolitans arrange both their global and local orientations. Aside offering scholars a new theoretical lens regarding consumer cosmopolitanism, managers can benefit from the gained insights, if cosmopolitans are a particular target group in their business strategy. The third and final essay meta-analytically investigates how the variables perceived brand globalness and localness materialize on various key outcome variables. At heart of this essay is a comparison of both perceived brand globalness and localness, offering scholars and practitioners valuable empirical insights on similarities and differences between their effects on outcomes such as brand quality. KW - global brands KW - local brands KW - perceived brand globalness KW - perceived brand localness KW - international marketing Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10722 ER - TY - THES A1 - Tomek, Raphaela T1 - Quiet please! - School Noise and its Effects on Student Teachers and Practicing Teachers N2 - Lärm in Schulen gilt aus unterschiedlichen Gründen als massiver Belastungsfaktor für Lehrkräfte und kann deshalb zu Leistungsdefiziten im Beruf, aber auch zu physischen und psychischen Beeinträchtigungen führen. Die Erforschung von Schullärm und seinen Auswirkungen ist daher essentiell. Die drei Studien, die in dieser Arbeit vorgestellt werden, untersuchten die unmittelbaren Auswirkungen von Lärm auf Lehramtsstudierende und die mittelbaren Auswirkungen auf praktizierende Lehrkräfte. In der ersten und zweiten Studie wurde im Rahmen zweier Experimente überprüft, wie sich Pausenlärm auf das Stresserleben, die Leistung in einem Konzentrationstest und auf die Fehlerkorrektur eines Diktats auswirkt. Auf Grundlage des transaktionalen Stressmodells (Lazarus & Folkman, 1984) wurde vermutet, dass Lärm zu einer Erhöhung des Stresserlebens führt. Der Maximal-Adaptability-Theorie (Hancock & Warm, 1989, 2003) nach sollte der Lärm zunächst eine optimale Leistung, langfristig jedoch eine Leistungsbeeinträchtigung verursachen. Um dies zu überprüfen, bearbeiteten in der ersten Studie 74 und in der zweiten Studie 104 Lehramtsstudierende der Universität Passau zwei unterschiedliche Konzentrationstests und korrigierten das Diktat eines Schülers, während sie kurzen, kontinuierlichen oder keinen Pausenlärm hörten. In beiden Experimenten führte kontinuierlicher Lärm zu einer Erhöhung des Stresserlebens. Weder kurzer noch kontinuierlicher Lärm führte zu einer Verschlechterung der Konzentrationsleistung. Weiter zeigten sich unterschiedliche Befunde: Im ersten Experiment führte ein kurzer Konzentrationstest in Kombination mit kontinuierlichem Lärm zu positiven Effekten in der Diktatkorrektur, d.h. die Versuchspersonen wiesen eine bessere Leistung in der Fehlerkorrektur auf. Im zweiten Experiment führte ein langer Konzentrationstest in Kombination mit kurzem oder kontinuierlichem Lärm zu negativen Effekten, d.h. die Probanden machten vergleichsweise mehr Fehler bei der anschließenden Diktatkorrektur. Daraus lässt sich schlussfolgern, dass Schullärm einerseits das Stresserleben erhöhen und andererseits die anschließende Leistungsfähigkeit der Lehrkräfte verbessern oder einschränken kann. Letzteres scheint allerdings von der konkreten Situation abzuhängen. Im ersten Teil der dritten Studie lag der Fokus auf den Bewältigungsstilen und dem erlebten Stress der Lehrkräfte. Da Bewältigungsstile nachweislich einen großen Einfluss auf die psychische Gesundheit haben, lag die Vermutung nahe, dass das durch Lärm verursachte Stresserleben je nach Bewältigungsstil unterschiedlich ausfällt. Auf der Grundlage des Belastungs-Beanspruchungsmodells (Rudow, 2000) und des transaktionalen Stressmodells (Lazarus & Folkman, 1984) wurde angenommen, dass Lehrkräfte mit riskanten Copingstilen mehr Stresssymptome erleben. Deshalb wurde im Rahmen einer Online-Studie untersucht, ob es in Bezug auf psychische und körperliche Symptome Unterschiede zwischen Lehrkräften mit distinkten Bewältigungsstilen gibt. Dazu wurden 99 bayerische Grund- und Mittelschullehrkräfte befragt. Aus den übergeordneten Skalen Engagement und Resilienz resultierten vier berufliche Bewältigungsstile. Der Typ Gesundheit (hohes Engagement, hohe Resilienz), der Schon-Typ (niedriges Engagement, hohe Resilienz), Typ A (hohes Engagement, niedrige Resilienz) und Typ Burnout (niedriges Engagement, niedrige Resilienz) unterschieden sich hinsichtlich Bedrohungseinschätzung, Lärmstress, Stimm- und Hörproblemen sowie lärmbedingtem Burnout. Im Vergleich zum Typ Gesundheit wiesen die Risikotypen Typ A und Typ Burnout ein höheres Stresserleben auf und erwiesen sich generell anfälliger gegenüber Schullärm als der Typ Gesundheit. Dies ist die erste Studie, die zeigen konnte, dass Schullärm besonders für Lehrkräfte mit riskanten Copingstilen eine Gefährdung darstellt. Im zweiten Teil der dritten Studie lag der Fokus auf den Wirkungspfaden von Schullärm. Hier wurden Zusammenhänge zwischen individuellen Eigenschaften der Lehrkräfte und den unterschiedlichen Auswirkungen von Schullärm vermutet. Basierend auf dem vereinfachten Modell von Lehrerstress (van Dick & Wagner, 2001) wurde an 159 bayerischen Grund- und Mittelschullehrkräften untersucht, ob Lärmstress und Stimmermüdung die Verbindung zwischen Lärmempfindlichkeit und lärmbedingtem Burnout vermitteln. Die Ergebnisse zeigten, dass Stress die Beziehung zwischen Lärmempfindlichkeit und Stimmermüdung vermittelte; Stimmermüdung vermittelte die Beziehung zwischen Lärmstress und lärmbezogenem Burnout; Lärmstress und Stimmermüdung vermittelten seriell die Beziehung zwischen Lärmempfindlichkeit und lärmbedingtem Burnout. Dies ist die erste Studie die Verbindungen zwischen lärmempfindlichen Lehrkräften und Lärmstress, Stimmproblemen und lärmbedingtem Burnout aufzeigen konnte. N2 - Noise in schools is considered a massive stress factor for teachers because of various reasons and can therefore lead to performance deficits in the job, but also to physical and psychological impairments. Consequently, research on school noise and its effects is essential. The three studies presented in this paper examined the immediate effects of noise on student teachers and the collateral effects on practicing teachers. In the first and second study, two experiments were conducted to examine the effects of noise during breaks on stress experience, performance in a concentration test, and error correction of a dictation. Based on the transactional stress model (Lazarus & Folkman, 1984), it was hypothesized that noise leads to an increase in stress experience. According to the maximal adaptability theory (Hancock & Warm, 1989, 2003), noise should initially cause optimal performance, but in the long run should cause performance impairment. For this purpose, in the first study 74 and in the second study 104 student teachers of the University of Passau worked on two different concentration tests and corrected a student’s dictation while listening to short, continuous, or no noise. In both experiments, continuous noise led to an increase in the experience of stress. Neither short nor continuous noise led to a deterioration in concentration performance. Further, different findings emerged: In the first experiment, a short concentration test in combination with continuous noise led to positive effects in dictation correction, i.e., subjects showed better performance in error correction. In the second experiment, a long concentration test combined with short or continuous noise resulted in negative effects, i.e., subjects made more errors in the subsequent correction of dictation. It can be concluded that school noise can, on the one hand, increase the experience of stress and, on the other hand, promote or limit teachers’ subsequent performance. The latest, however, seems to depend on the specific situation of the individual. In the first part of the third study, the focus was on teachers’ coping styles and experienced stress. Since coping styles have been shown to have a major impact on mental health, it was reasonable to assume that the stress experience caused by noise would vary depending on the coping style. Based on the stress-strain model (Rudow, 2000) and the transactional stress model (Lazarus & Folkman, 1984), it was hypothesized that teachers with risky coping styles experience more stress symptoms. Therefore, an online study was conducted to investigate whether there were differences in psychological and physical symptoms between teachers with different coping styles. For this purpose, 99 Bavarian elementary and middle school teachers were surveyed. Four professional coping styles resulted from the overarching scales of professional commitment and resilience. The healthy type (high commitment, high resilience), the unambitious type (low commitment, high resilience), type A (high commitment, low resilience), and type burnout (low commitment, low resilience) differed in terms of threat appraisal, noise stress, voice and hearing problems, and noise-related burnout. Compared to the healthy type, the risk types − type A and type burnout − exhibited higher stress experience and were generally more susceptible to school noise than the healthy type. This is the first study to show that school noise is particularly hazardous for teachers with risky coping styles. The second part of the third study focused on the impact pathways of school noise. Associations between teachers’ individual characteristics and the consequences of school noise were hypothesized. Based on the simplified model of teacher stress (van Dick & Wagner, 2001), we examined 159 Bavarian elementary and middle school teachers to determine whether noise stress and vocal fatigue mediate the association between noise sensitivity and noise-related burnout. Results indicated that noise stress mediated the relationship between noise sensitivity and vocal fatigue; vocal fatigue mediated the relationship between noise stress and noise-related burnout; noise stress and vocal fatigue serially mediated the relationship between noise sensitivity and noise-related burnout. This is the first study to show links between noise-sensitive teachers and noise stress, voice problems, and noise-related burnout. KW - school noise KW - teacher stress KW - student teachers KW - practicing teachers KW - performance Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10626 ER - TY - THES A1 - Steudner, Tobias T1 - Understanding Consumers' Digital Data Disclosure Decision-Making: A Focus on Data Sharing Cooperations, Perceived Risks and Low-Cognitive-Effort Processing N2 - Due to the advances of digitalization, firms are able to collect more and more personal consumer data and strive to do so. Moreover, many firms nowadays have a data sharing cooperation with other firms, so consumer data is shared with third parties. Accordingly, consumers are confronted regularly with the decision whether to disclose personal data to such a data sharing cooperation (DSC). Despite privacy research has become highly important, peculiarities of such disclosure settings with a DSC between firms have been neglected until now. To address this gap is the first research objective in this thesis. Another underexplored aspect in privacy research is the impact of low-cognitive-effort decision-making. This is because the privacy calculus, the most dominant theory in privacy research, assumes for consumers a purely cognitive effortful and deliberative disclosure decision-making process. Therefore, to expand this perspective and examine the impact of low-cognitive-effort decision-making is the second research objective in this thesis. Additionally, with the third research objective, this thesis strives to unify and increase the understanding of perceived privacy risks and privacy concerns which are the two major antecedents that reduce consumers’ disclosure willingness. To this end, five studies are conducted: i) essay 1 examines and compares consumers’ privacy risk perception in a DSC disclosure setting with disclosure settings that include no DSC, ii) essay 2 examines whether in a DSC disclosure setting consumers rely more strongly on low-cognitive-effort processing for their disclosure decision, iii) essay 3 explores different consumer groups that vary in their perception of how a DSC affects their privacy risks, iv) essay 4 refines the understanding of privacy concerns and privacy risks and examines via meta-analysis the varying effect sizes of privacy concerns and privacy risks on privacy behavior depending on the applied measurement approach, v) essay 5 examines via autobiographical recall the effects of consumers’ feelings and arousal on disclosure willingness. Overall, this thesis shines light on consumers’ personal data disclosure decision-making: essay 1 shows that the perceived risk associated with a disclosure in a DSC setting is not necessarily higher than to an identical firm without DSC. Also, essay 3 indicates that only for the smallest share of consumers a DSC has a negative impact on their disclosure willingness and that one third of consumers do not intensively think about consequences for their privacy risks arising through a DSC. Additionally, essay 2 shows that a stronger reliance on low-cognitive-effort processing is prevalent in DSC disclosure settings. Moreover, essay 5 displays that even unrelated feelings of consumers can impact their disclosure willingness, but the effect direction also depends on consumers’ arousal level. This thesis contributes in three ways to theory: i) it shines light on peculiarities of DSC disclosure settings, ii) it suggests mechanisms and results of low-effort processing, and iii) it enhances the understanding of perceived privacy risks and privacy concerns as well as their resulting effect sizes. Besides theoretical contributions, this thesis offers practical implications as well: it allows firms to adjust the disclosure setting and the communication with their consumers in a way that makes them more successful in data collection. It also shows that firms do not need to be too anxious about a reduced disclosure willingness due to being part of a DSC. However, it also helps consumers themselves by showing in which circumstances they are most vulnerable to disclose personal data. That consumers become conscious of situations in which they are especially vulnerable to disclose data could serve as a countermeasure: this could prevent that consumers disclose too much data and regret it afterwards. Similarly, this thesis serves as a thought-provoking input for regulators as it emphasizes the importance of low-cognitive-effort processing for consumers’ decision-making, thus regulators may be able to consider this in the future. In sum, this thesis expands knowledge on how consumers decide whether to disclose personal data, especially in DSC settings and regarding low-cognitive-effort processing. It offers a more unified understanding for antecedents of disclosure willingness as well as for consumers’ disclosure decision-making processes. This thesis opens up new research avenues and serves as groundwork, in particular for more research on data disclosures in DSC settings. KW - Privacy KW - Disclosure KW - Dual Processing KW - Emotion KW - Privacy Concerns Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10583 ER - TY - THES A1 - Lenz, Luciane T1 - The diffusion of modern energy technologies in low-income settings - evidence from rural sub-Saharan Africa N2 - This collection of three chapters responds to today’s energy challenges. It explores innovative policy aimed to equip the energy poor with access to improved cooking energy and electricity, looking both at the demand and supply side of modern energy technologies. Concretely, it discusses mechanisms to increase uptake of off-grid solar electricity in rural Rwanda based on experimental demand measurements (Chapter 1), it studies how to diffuse improved cooking technologies in rural Senegal via supply-side mechanisms (Chapter 2), and it identifies the need to target cooking technologies in consideration of the broader household context in rural Senegal and beyond (Chapter 3). KW - Technology adoption KW - Energy access KW - Rural development KW - Subsaharisches Afrika KW - Armut KW - Energietechnik KW - Erneuerbare Energien Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10550 ER - TY - THES A1 - Beierl, Stefan T1 - Public Works Programmes: Review of their effectiveness and empirical essays on their contribution to climate resilience and social cohesion N2 - Poverty, underemployment, lack of infrastructure, low agricultural productivity, degradation of natural resources, climate change, and eroding social cohesion are among the biggest challenges that many low and lower-middle income countries are facing. Objectives linked to addressing these pressing challenges have been ascribed to public works programmes (PWPs). These are social protection instruments which offer remuneration (in cash or kind) for vulnerable people in exchange for temporary work on labour-intensive low-skill activities with social benefits. PWPs are being implemented in around two out of three developing countries. Given the substantial amounts spent on PWPs, it is critical to know to what extent the expectations towards them are backed by evidence. This dissertation sheds light on this overarching question with three self-contained essays. The first essay synthesises the evidence from PWPs in Sub-Saharan Africa, guided by three questions: First, what can we infer from the available impact evaluations regarding the effectiveness of PWPs as a social protection instrument? Second, what do we know about the role of the wage vector, asset vector, and skills vector in this respect? Third, what can we infer about the role of design features in explaining differences in outcomes? The other two essays use empirical evidence from Malawi to address more specific questions regarding the potential of PWPs to strengthen climate resilience and the relationship between PWPs and social cohesion. What sets the evidence synthesis in my first essay apart from existing reviews of PWPs is that it accounts for their heterogeneity by systematically differentiating results by PWP type and outcome area (income, consumption and expenditures, labour supply, food security, nutrition, asset holdings, agricultural production and techniques, and education). Programmes that offer short-term ad-hoc employment (Type 1) are distinguished from programmes that offer more predictable employment over longer periods (Type 2). For the review of impacts, this paper relies solely on (quasi-)experimental studies, but for the analysis of the role of design factors also on other literature. In line with existing reviews, my results suggest that Type 1 programmes can effectively enable consumption smoothing in the wake of acute crises, whereas in contexts of chronic poverty, Type 2 programmes perform, on balance, better. Offering complementary access to extension services in Type 2 programmes can boost impacts further. However, in all cases, evidence is too scant and mixed to safely conclude whether the higher benefits of costlier PWP types justify the cost premium. The second essay investigates the potential of PWPs to strengthen climate resilience. Among the main social protection instruments, the biggest potential to strengthen climate resilience is often ascribed to PWPs if they create climate-smart community assets and transfer knowledge of climate-smart practices. Yet, there is a lack of evidence whether design changes to this end can indeed enhance the contribution of an existing PWP to climate resilience. I use a difference-in-differences approach based on two-period panel data to analyse how a modified PWP model performs compared to the standard model of Malawi’s largest PWP after 24 months. The key modification is to embed public works in a communal watershed management plan with a strong emphasis on collective action and capacity building. I find that the modified approach considerably increased communal watershed management activities through voluntary labour contributions on top of the paid public works labour. While this increase was mainly driven by PWP participants, non-participants also made substantial contributions. I also find a small increase in the adoption of soil and water conservation practices on respondents’ private land, especially by non-PWP participants. These findings imply that such modest changes can make PWPs climate-smarter. In particular, they can broaden the engagement in and adoption of climate-smart activities beyond the group of PWP participants. The co-authored third essay investigates the relationship between Malawi’s MASAF PWP and social cohesion, specifically within-community cooperation for the common good. Like the existing studies, we face the challenge that neither the assignment of the programme to communities nor the selection of individual participants is randomised. We try to mitigate the endogeneity concerns by triangulating fixed effects panel analyses for a set of outcomes and sectors using two datasets with different units of analysis (households and communities). We find that public works are positively associated with coordination activities and voluntary (unpaid) contributions to public goods, along both vertical ties (between community members and local leaders) and horizontal ties (among community members). Especially for school-building activities, voluntary inputs in the form of labour and other in-kind contributions are higher in the presence of the public works programme. Our results contribute to a better understanding of the link between social protection programmes with community-driven features and social cohesion. Overall, the findings of the three essays in this dissertation contribute to the knowledge base regarding effectiveness and potential of PWPs across a broad range of outcome areas. Specifically, they offer new insights how to harness the potential of PWP to strengthen climate resilience and into the seemingly positive relationship between PWPs and social cohesion. The findings can help researchers and policy makers who are interested specifically in PWPs or in any of the many objectives that can be pursued through PWPs. KW - Public Works KW - Social Protection KW - Social cohesion KW - Review KW - Climate resilience Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10491 ER - TY - THES A1 - Luck, Nathalie T1 - Transformation towards a more sustainable agricultural system in Indonesia: Empirical essays on the role of information and endorsement N2 - In many cases, transitioning towards sustainable agricultural production requires farmers to change their practices. These changes can include the adoption of sustainable agricultural practices, water-saving, or the disadoption of excessive chemical input use or land burning. Policy makers interested in making agricultural production more sustainable need to understand what encourages the uptake of sustainable practices and what is effective in reducing unsustainable practices. This thesis seeks to understand whether and how information provision and endorsement can contribute to the transition towards more sustainable agricultural systems. The thesis consists of three self-contained papers. The first paper explores the potential of religious endorsement for inducing pro-environmental behaviour and encouraging the disadoption of fire as an agricultural practice, thereby preventing forest fires. The paper analyses the impact of a fatwa (an Islamic religious ruling) on reducing fire incidence in Indonesia. Results indicate that fire incidence decreased in Muslim majority villages following the issuing of the fatwa. For the post-fatwa period from August 2016 to December 2019, the average monthly effect amounts to around 2.2 prevented fire events per village. This is a considerable effect. The paper concludes that fire prevention efforts, and potentially other environmental conservation efforts, could benefit significantly from support by religious institutions and stakeholders. The second paper investigates the role of information provision and training for the adoption of organic farming practices in Java, Indonesia. We use a randomised controlled trial (RCT) to identify the impact of a three-day hands-on training in organic farming for smallholder farmers. We find that the training intervention increased the adoption of organic inputs and had a positive and statistically significant effect on farmers’ knowledge and perceptions of organic farming. Overall, our findings suggest that information constraints are a barrier to the adoption of organic farming, as information provision increased the use of organic farming practices. The third paper investigates whether urban and suburban Indonesian consumers are willing to pay a price premium for organic food. We use an incentive-compatible auction based on the Becker-DeGroot-Marschak (BDM) approach to elicit consumers’ WTP. We further study the effect of income and a randomised information treatment about the benefits of organic food on respondents’ WTP. Estimates suggest that consumers are willing to pay a price premium for organic rice, on average 20 percent more than what they paid for conventional rice outside of our experiment. However, our results also indicate that raising consumers’ WTP further is complex. Showing participants a video about the health or, alternatively, environmental benefits of organic food was not effective in further raising WTP. Exposure to the environmental benefits video was, however, effective in raising stated organic food consumption intentions. KW - technology adoption, religion, organic farming, WTP KW - Landwirtschaft KW - Nachhaltigkeit KW - Entwicklungsökonomie Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10037 ER - TY - THES A1 - Behm, Svenia T1 - Four essays on statistical modelling of environmental data N2 - This dissertation deals with geostatistical, time series, and regression analytical approaches for modelling spatio-temporal processes, using air quality data in the applications. The work is structured into four essays the abstracts of which are given in the following. The first essay is titled 'Spatial detrending revisited: Modelling local trend patterns in NO2-concentration in Belgium and Germany'. It is written in co-authorship by Prof. Dr. Harry Haupt and Dr. Angelika Schmid and published in 2018 in Spatial Statistics 28, pp. 331-351 (https://doi.org/10.1016/j.spasta.2018.04.004). Abstract Short-term predictions of air pollution require spatial modelling of trends, heterogeneities, and dependencies. Two-step methods allow real-time computations by separating spatial detrending and spatial extrapolation into two steps. Existing methods discuss trend models for specific environments and require specification search. Given more complex environments, specification search gets complicated by potential nonlinearities and heterogeneities. This research embeds a nonparametric trend modelling approach in real-time two-step methods. Form and complexity of trends are allowed to vary across heterogeneous environments. The proposed method avoids ad hoc specifications and potential generated predictor problems in previous contributions. Examining Belgian and German air quality and land use data, local trend patterns are investigated in a data driven way and are compared to results computed with existing methods and variations thereof. An important aspect of our empirical illustration is the heterogeneity and superior performance of local trend patterns for both research regions. The findings suggest that a nonparametric spatial trend modelling approach is a valuable tool for real-time predictions of pollution variables: it avoids specification search, provides useful exploratory insights and reduces computational costs. The second essay is titled 'Predictability of hourly nitrogen dioxide concentration'. It is written in co-authorship with Prof. Dr. Harry Haupt and published in 2020 in Ecological Modelling 428, 109076 (https://doi.org/10.1016/j.ecolmodel.2020.109076). Abstract Temporal aggregation of air quality time series is typically used to investigate stylized facts of the underlying series such as multiple seasonal cycles. While aggregation reduces complexity, commonly used aggregates can suffer from non-representativeness or non-robustness. For example, definitions of specific events such as extremes are subjective and may be prone to data contaminations. The aim of this paper is to assess the predictability of hourly nitrogen dioxide concentrations and to explore how predictability depends on (i) level of temporal aggregation, (ii) hour of day, and (iii) concentration level. Exploratory tools are applied to identify structural patterns, problems related to commonly used aggregate statistics and suitable statistical modeling philosophies, capable of handling multiple seasonalities and non-stationarities. Hourly times series and subseries of daily measurements for each hour of day are used to investigate the predictability of pollutant levels for each hour of day, with prediction horizons ranging from one hour to one week ahead. Predictability is assessed by time series cross validation of a loss function based on out-of-sample prediction errors. Empirical evidence on hourly nitrogen dioxide measurements suggests that predictability strongly depends on conditions (i)-(iii) for all statistical models: for specific hours of day, models based on daily series outperform models based on hourly series, while in general predictability deteriorates with exposure level. The third essay is titled 'Agglomeration and infrastructure effects in land use regression models for air pollution – Specification, estimation, and interpretations'. It is written in co-authorship with Dr. Markus Fritsch and published in 2021 in Atmospheric Environment 253, 118337 (https://doi.org/10.1016/j.atmosenv.2021.118337). Abstract Established land use regression (LUR) techniques such as linear regression utilize extensive selection of predictors and functional form to fit a model for every data set on a given pollutant. In this paper, an alternative to established LUR modeling is employed, which uses additive regression smoothers. Predictors and functional form are selected in a data-driven way and ambiguities resulting from specification search are mitigated. The approach is illustrated with nitrogen dioxide (NO2) data from German monitoring sites using the spatial predictors longitude, latitude, altitude and structural predictors; the latter include population density, land use classes, and road traffic intensity measures. The statistical performance of LUR modeling via additive regression smoothers is contrasted with LUR modeling based on parametric polynomials. Model evaluation is based on goodness of fit, predictive performance, and a diagnostic test for remaining spatial autocorrelation in the error terms. Additionally, interpretation and counterfactual analysis for LUR modeling based on additive regression smoothers are discussed. Our results have three main implications for modeling air pollutant concentration levels: First, modeling via additive regression smoothers is supported by a specification test and exhibits superior in- and out-of-sample performance compared to modeling based on parametric polynomials. Second, different levels of prediction errors indicate that NO2 concentration levels observed at background and traffic/industrial monitoring sites stem from different processes. Third, accounting for agglomeration and infrastructure effects is important: NO2 concentration levels tend to increase around major cities, surrounding agglomeration areas, and their connecting road traffic network. The fourth essay is titled 'Outlier detection and visualisation in multi-seasonal time series and its application to hourly nitrogen dioxide concentration'. It is written in single authorship and has not been published yet. Abstract Outlier detection in data on air pollutant recordings is conducted to uncover data points that refer to either invalid measurements or valid but unusually high concentration levels. As air pollutant data is typically characterised by multiple seasonalities, the task of outlier detection is associated with the question of how to deal with such non-stationarities. The present work proposes a method that combines time series segmentation, seasonal adjustment, and standardisation of random variables. While the former two are employed to obtain subseries of homoskedastic data, the latter ensures comparability across the subseries. Further, the standardised version of the seasonally adjusted subseries represents a scaled measure for the outlyingness of each data point in the original time series from its mean and therefore forms a suitable basis for outlier detection. In an empirical application to data on hourly NO2 concentration levels recorded at a traffic monitoring site in Cologne, Germany, over the years 2016 to 2019, the common boxplot criterion is used to examine each standardised seasonally adjusted subseries for positive outliers. The results of the analyses are put into their natural temporal order and displayed in a heatmap layout that provides information on when single and sequential outliers occur. KW - Spatio-temporal modelling KW - time series analysis KW - regression KW - geostatistics KW - multiple seasonalities KW - environmental data KW - Statistik KW - Geostatistik KW - Umweltdaten Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10539 ER - TY - THES A1 - Zierke, Oliver T1 - Innovation and Competition in the Digital Economy: Implications for Internet Platforms, Telecommunications Networks and Data Sharing Initiatives N2 - Governments around the world currently focus on shaping the digital economy. Particular attention is paid to Internet platforms, Internet infrastructure and data as essential components of the digital economy. The three studies in this thesis contribute to the understanding of the behavior of firms in each of these domains and derive insights for future regulations and business projects. The first study deals with the ranking of content on Internet platforms and how it affects the incentives of content providers to invest in content quality. The focus of the study is on sponsored ranking and organic ranking, but the case that a vertically integrated content provider is favored by an Internet platform is also taken into account. Using a game theoretic model, it is shown that there is no ranking design that strictly leads to more investment compared to the other designs. It is also shown that the Internet platform usually chooses the type of ranking that, from the perspective of the Internet platform and consumers, yields the best expected overall content quality. The second study deals with the incentive of Internet service providers to throttle specific Internet content. The key finding is that Internet service providers use this instrument to utilize the capacity of their telecommunications network more efficiently. This leads not only to more benefits for Internet users, but also to a higher incentive to invest in network capacity due to better monetization. The third study examines the circumstances under which firms are willing to share data with other firms. By means of an economic laboratory experiment, it is shown that more data is shared if the firms have control over who exactly they share data with. Thus, for example, data pools that grant unrestricted data access to all participating firms can be expected to perform worse than data pools that give their participating firms control over with whom their uploaded data is shared. In addition, the third study finds that established relationships are characterized by more data sharing and less volatility in the amount of shared data than new relationships. The study concludes that data sharing projects should not be expected to work optimally right away. In summary, the studies in this thesis identify a number of costs that may arise when digital firms' choice is restricted by regulation or design. The ability of Internet service providers to throttle certain content and the ability of Internet platforms to choose the ranking design are usually used in the best interests of consumers. Data sharing also works best when firms are free to decide who gets their data. KW - online platform KW - ranking algorithm KW - sponsored search KW - platform regulation KW - net neutrality Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10006 ER - TY - THES A1 - Mini, Tobias T1 - An Exploration of Tensions in Centralized and Decentralized Digital Platform Contexts N2 - Digital platforms consist of technical elements such as software and hardware and associated social elements such as organizational processes and standards. When such social or technical elements seem logical individually but inconsistent when juxtaposed they form tensions. Prior research on platforms often focused on individual elements of digital platforms but neglected possible related and conflicting elements which offers limited insight about underlying tensions. While some studies on platforms considered tensions, they largely assumed that centralized platform owners being responsible for responding to tensions, neglecting collective response mechanisms in blockchain-based decentralized autonomous organizations (DAOs) where decentralized participants typically respond to tensions. The examination of tensions in the context of centralized platforms and decentralized autonomous organizations offers an opportunity to surface conflicting elements that form novel types of socio-technical tensions which require collective and technology-enabled response mechanisms. This thesis explored what tensions exist in centralized and decentralized digital platform contexts and how platform participants can respond to selected tensions. For this purpose, this thesis comprises five essays that employ multiple different research methods including interviews analyzed by using techniques of grounded theory, qualitative meta-analysis of published case studies, and systematic literature reviews. The findings derived from all five essays contribute to a better understanding of tensions in digital platforms. In particular, this thesis (1) offers a lens for analyzing platforms as collective organizations in which tensions arise at the collective meta-organizational level requiring collective responses, (2) identifies new tensions and response mechanisms related to generativity and collectivity, and (3) points to a novel category of socio-technical tensions that are especially salient in digital platforms. KW - Digital Platform KW - Decentralized Autonomous Organization KW - Tension KW - Grounded Theory Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11322 ER - TY - THES A1 - Resch, René Matthias T1 - Three Essays on Brand Management in the Business-to-Business Context: Brand Identity, Brand Culture, and Brand Essence N2 - This dissertation examines the overarching research question of how the suppliers’ brand management in the form of brand identity, brand culture, and brand essence influences buyer-seller relationships in three independent essays. In Essay 1, I address the structure, capabilities, and outcomes of brand identity from a supplier perspective. Through qualitative interviews with suppliers, I examine how widespread the concept of brand identity is in practice and what exactly practitioners understand by it. Going further, I look at what capabilities and conditions are necessary for brand identity to be successful and what outcomes suppliers hope to achieve. Using an Information-Display-Matrix (IDM) test and a sample of Master of Business Administration (MBA) students, I examine the relevance of brand functions in more detail. In Essay 2, I use a dyadic dataset with matched buyer-seller dyads to examine the causes and effects of perceptual congruence and incongruence of brand culture strength on the buyer-seller relationship, while considering relationship-specific investments and interaction mechanisms as moderating effects. I show that congruence and incongruence have different effects on customer loyalty and price sensitivity and that these are strongly context-dependent. In Essay 3, I deal with brand essence strength interactions and their effects on the buyer-seller relationship. I use a dyadic dataset with matched buyer-seller dyads to show how brand essence strength influences customer loyalty and customer profitability, and how it interacts with key customer attitudes and other important buyer-seller relationship closeness indicators. This dissertation makes a significant contribution to the literature on brand identity, brand culture, and brand essence in buyer-seller relationships. Furthermore, my dissertation offers practical implications for managers at B2B suppliers who (re)shape their brand management with a focus on the inner parts of the brand. KW - brand management KW - business-to-business KW - brand identity KW - brand culture KW - brand essence Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11589 ER - TY - THES A1 - Liang, Hanning T1 - Deflectometric Measurement of the Topography of Reflecting Freeform Surfaces in Motion N2 - Measuring the topography of specular surfaces with strong surface structures in motion was impossible before this research. A new method based on singleshot phase-measuring de ectometry (SSPMD) and combining different solution aspects has been presented. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11672 ER - TY - THES A1 - Wharton, David T1 - Language, Orthography and Buddhist Manuscript Culture of the Tai Nuea - an apocryphal jātaka text in Mueang Sing, Laos N2 - The focus of this study is a single manuscript in a Tai Nuea village near Mueang Sing in northwestern Laos, copied in 1935 and entitled Pukthanusati (Pali buddhānussati) ‘the Recollection of the Buddha.’ It is written in the Tai Nuea language and Lik Tho Ngok or ‘Bean Sprout’ script, and is in the form of a jātaka or narrative story of a former lifetime of the Buddha, the most popular genre for recitation. The thesis examines the lay manuscript culture of which it is a part and the language and orthography of its contents, and then provide a phonemic transcription and annotated English translation of the text together a complete glossary of terms and images of the manuscript. The detailed study of this one manuscript is used as an entry point for a broader investigation of Lik manuscript culture as found in Mueang Sing today, including the distinct roles of the Lik and Tham orthographies, scribal vocation, manuscript production, uses and functions, and the contents of the texts. The Pukthanusati text is then the basis for examination of phonological aspects of language use in the recitation of Lik manuscript literature and the historical context of the dialect’s phonemes as well as Burmese and Indic forms occurring as loanwords. The Lik Tho Ngok orthography is also placed in context through an overview of its historical development, including possible prototypes and phonological influences, the twentieth century reforms of some traditional orthographies and the question of orthographic depth. The Lik Tho Ngok orthography as found in the manuscript studied is then described in detail, with tables and accompanying notes illustrating the inventories of consonant and vowel glyphs, consonant clusters, ligatures and special orthographic forms, use of subscripts and superscripts, numerals, punctuation, and the Tai Nuea spelling system. The phonemic transcription and annotated English translation of the text illustrate the rhyming structure and other features of specialised language use in Lik manuscript culture. The Tai Nuea and a number of closely related Tai groups have generally been overlooked in the field of Buddhist Studies. The study of this manuscript culture therefore contributes to our understanding of local practices on the northern periphery of Theravāda Buddhist influence in mainland Southeast Asia in addition to responding to an urgent need to examine and document this endangered scribal tradition and it specialised use of language and orthography. KW - Southeast Asia KW - Buddhism KW - Tai KW - Tai Nuea KW - Mueang Sing KW - Laos KW - Manuscript KW - Jataka KW - Apocryphal jataka KW - Linguistics KW - Orthography KW - Lik script KW - Literature KW - Buddhistische Literatur KW - Handschrift KW - Tai-Dehung KW - Linguistik Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-5236 ER - TY - THES A1 - Joblin, Mitchell T1 - Structural and Evolutionary Analysis of Developer Networks N2 - Large-scale software engineering projects are often distributed among a number sites that are geographically separated by a substantial distance. In globally distributed software projects, time zone issues, language and cultural barriers, and a lack of familiarity among members of different sites all introduce coordination complexity and present significant obstacles to achieving a coordinated effort. For large-scale software engineering projects to satisfy their scheduling and quality goals, many developers must be capable of completing work items in parallel. A key factor to achieving this goal is to remove interdependencies among work items insofar as possible. By applying principles of modularity, work item interdependence can be reduced, but not removed entirely. As a result of uncertainty during the design and implementation phases and incomplete or misunderstood design intents, dependencies between work items inevitably arises and leads to requirements for developers to coordinate. The capacity of a project to satisfy coordination needs depends on how the work items are distributed among developers and how developers are organizationally arranged, among other factors. When coordination requirements fail to be recognized and appropriately managed, anecdotal evidence and prior empirical studies indicate that this condition results in decreased product quality and developer productivity. In essence, properties of the socio-technical environment, comprised of developers and the tasks they must complete, provides important insights concerning the project's capacity to meet product quality and scheduling goals. In this dissertation, we make contributions to support socio-technical analyses of software projects by developing approaches for abstracting and analyzing the technical and social activities of developers. More specifically, we propose a fine-grained, verifiable, and fully automated approach to obtain a proper view on developer coordination, based on commit information and source-code structure, mined from version-control systems. We apply methodology from network analysis and machine learning to identify developer communities automatically. To evaluate our approach, we analyze ten open-source projects with complex and active histories, written in various programming languages. By surveying 53 open-source developers from the ten projects, we validate the accuracy of the extracted developer network and the authenticity of the inferred community structure. Our results indicate that developers of open-source projects form statistically significant community structures and this particular network view largely coincides with developers' perceptions. Equipped with a valid network view on developer coordination, we extend our approach to analyze the evolutionary nature of developer coordination. By means of a longitudinal empirical study of 18 large open-source projects, we examine and discuss the evolutionary principles that govern the coordination of developers. We found that the implicit and self-organizing structure of developer coordination is ubiquitously described by non-random organizational principles that defy conventional software-engineering wisdom. In particular, we found that: (a) developers form scale-free networks, in which the majority of coordination requirements arise among an extremely small number of developers, (b) developers tend to accumulate coordination requirements with more and more developers over time, presumably limited by an upper bound, and (c) initially developers are hierarchically arranged, but over time, form a hybrid structure, in which highly central developers are hierarchically arranged and all other developers are not. Our results suggest that the organizational structure of large software projects is constrained to evolve towards a state that balances the costs and benefits of coordination, and the mechanisms used to achieve this state depend on the project's scale. As a final contribution, we use developer networks to establish a richer understanding of the different roles that developers play in a project. Developers of open-source projects are often classified according to core and peripheral roles. Typically, count-based operationalizations, which rely on simple counts of individual developer activities (e.g., number of commits), are used for this purpose, but there is concern regarding their validity and ability to elicit meaningful insights. To shed light on this issue, we investigate whether count-based operationalizations of developer roles produce consistent results, and we validate them with respect to developers' perceptions by surveying 166 developers. We improve over the state of the art by proposing a relational perspective on developer roles, using our fine-grained developer networks, and by examining developer roles in terms of developers' positions and stability within the developer network. In a study of 10 substantial open-source projects, we found that the primary difference between the count-based and our proposed network-based core--peripheral operationalizations is that the network-based ones agree more with developer perception than count-based ones. Furthermore, we demonstrate that a relational perspective can reveal further meaningful insights, such as that core developers exhibit high positional stability, upper positions in the hierarchy, and high levels of coordination with other core developers, which confirms assumptions of previous work. Overall, our research demonstrates that data stored in software repositories, paired with appropriate analysis approaches, can elicit valuable, practical, and valid insights concerning socio-technical aspects of software development. KW - Software Engineering Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-4616 ER - TY - THES A1 - Schubach, Sebastian T1 - Caught between two stools? Four essays on value creation and value extraction on free digital platforms N2 - Free digital platforms constitute one of the most important phenomena of modern times; they create value by bringing together customer groups that would not have interacted without digital technology or that could have done so only by incurring increased costs. In the free digital platform model, firms pay for the interaction with end consumers that use the digital platform for free. Extant research on two-sided markets has provided rich evidence for how digital platforms can attract enough members from both customer groups to enable the interaction between the customer groups. However, this research lacks insights into how free digital platforms can create value for their customer groups once these customer groups joined the platform, and extract this value for themselves. To address this substantial research gap, in this dissertation, I investigate the overall research question of how activities of free digital platforms affect the value creation for their customer groups and the ability of the platform to extract this value. In a first step, I examine this value creation and value extraction by focusing on concrete activities of free digital platforms. In Study 1, I investigate how offering firms the possibility of personalizing and positioning their search ads on search engines affects consumers’ search engine click behavior. In Study 2, I examine how adapting ad positions to consumers’ previous online shopping behavior on search engines influences consumers’ click and conversion behavior. In Study 3, I investigate the impact of a review platform’s policy of tagging reviews as written on either mobile or nonmobile devices on consumers’ perceptions of review helpfulness. In a second step, in Study 4, I generalize these findings by investigating the overall impact of such customer-oriented activities on value creation for customer groups and on the extraction of this value by free digital platforms. These four studies yield three major findings. First, free digital platforms’ activities toward one customer group always affect the value creation of the other customer group as well. Second, free digital platforms should emphasize value creation activities especially for non-paying customer groups. Third, internal, operative, and macro-environments influence the value creation and value extraction of free digital platforms. With this dissertation, I make substantial contributions to research on two-sided markets, customer orientation, search engine advertising, and online reviews. In addition, my dissertation provides numerous actionable recommendations for managers of free digital platforms and outlines promising avenues for further research. N2 - Kostenfrei nutzbare Internetplattformen zählen zu den wichtigsten Phänomenen der digitalen Ära. In der Forschung bleiben sie aktuell jedoch weitestgehend unerforscht. Aus diesem Grund beschäftigt sich die vorliegende Dissertation anhand von vier empirischen Studie mit der Frage, wie Anbieter dieser kostenfrei nutzbaren Internetplattformen Wert für ihre Kunden schaffen und Wert für sich abschöpfen können. Die Ergebnisse der Dissertation halten wichtige Implikationen für die Forschung und die Unternehmenspraxis bereit. KW - Two-sided markets KW - Value creation KW - Free e-services KW - Value extraction KW - Digital platforms Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-6451 ER - TY - THES A1 - Zhu, Chunjie T1 - Understanding the Formation and Improving the Accuracy of Teacher Judgment N2 - Die Forschung zu Lehrkrafturteilen hat in den letzten drei Jahrzehnten beträchtliche Fortschritte gemacht. Die Bedeutung des Lehrkrafturteils und die Variabilität in der Urteilsgenauigkeit erfordern eine eingehendere Untersuchung. Basierend auf der Überprüfung früherer Studien wurde ein systematischer analytischer Rahmen vorbereitet, der aus drei Hauptstudien besteht, um das Verständnis der Prozesse und Merkmale von Lehrkrafturteilen zu erweitern. In den drei vorgestellten Studien wurde insbesondere untersucht, wie Lehrkrafturteile durch verschiedene Schülermerkmale generiert werden, welche Möglichkeiten es gibt, die Urteilsgenauigkeit von Lehrkräften zu verbessern und ob die Urteilsgenauigkeit von Lehrkräften im Laufe der Zeit stabil bleiben kann. In der ersten Studie wurde das Linsenmodell der Theorie der sozialen Beurteilung angewendet, um die Einschätzungen von Lehrpersonen über die Leistung von Schülerinnen und Schülern und ihre Strategien der Informationsverarbeitung besser zu verstehen. 260 Lehrkräfte aus sieben chinesischen Grundschulen wurden gebeten, aus sieben Informationsquellen Schülermerkmale auszuwählen und zu bewerten, anhand derer sie die Leistungen der Schüler beurteilen könnten. Die Lehrpersonen entwickelten eine klare Hierarchie der verwendeten Datenquellen. Die besten Informationen wurden aus den Fähigkeiten und Einstellungen der Schülerinnen und Schüler gewonnen und die am wenigsten wichtigen Informationen aus der sozialen Interaktion mit anderen sowie aus der Schüler-Demografie. Um genauere Einschätzungen zu treffen, sollten die Lehrkräfte über gültige Indikatoren für die Schülerleistung informiert werden. Die zweite Studie zielte darauf ab, die Urteilsgenauigkeit von Lehrkräften und die Leistung der Schülerinnen und Schüler durch den Einsatz von Classroom-Response-Systemen („Clickern“) zu fördern. 20 Schulklassen mit 459 Schülerinnen und Schülern der sechsten Klasse und ihren Mathematiklehrkräften wurden für eine fünfwöchige quasi-experimentelle Interventionsstudie mit einem Pre- und Post-Test in drei Gruppen eingeteilt. Die Ergebnisse zeigen, dass beide Ziele weitgehend erreicht werden konnten. Schülerinnen und Schüler der Clicker-Gruppe haben durch die Intervention mehr mathematisches Wissen erworben als Studenten der Tagebuch- und Kontrollgruppe. Die Lehrkrafturteile aller drei Gruppen wurden vom Pre- zum Post-Test genauer. Lehrpersonen, die Clicker verwendeten, beurteilten jedoch mit höchster Genauigkeit. Clicker können als wertvolles Werkzeug zur Verbesserung der Urteilsgenauigkeit von Lehrkräften empfohlen werden. In der dritten Studie wurde die zeitliche Stabilität der Urteilsgenauigkeit der Lehrkräfte hinsichtlich Motivation, Emotion und Leistung der Schülerinnen und Schüler untersucht. Neun Klassen mit 326 Sechstklässlern einer chinesischen Grundschule und ihren Mathematiklehrpersonen nahmen an der Studie teil. Die Schüler arbeiteten an einem standardisierten Mathematik-Test und einem Selbstbeschreibungsfragebogen zu Motivation und Emotion. Die Lehrpersonen beurteilten die Motivation, Emotion und Leistung jedes einzelnen Schülers anhand einzelner Items. Das Lehrkrafturteil und die Eigenschaften der Schülerinnen und Schüler wurden innerhalb von vier Wochen zweimal gemessen. Die Ergebnisse zeigten, dass die Lehrkräfte in der Lage waren, die Schülerleistungen mit hoher Genauigkeit, die Motivation der Schülerinnen und Schüler mit mäßiger bis hoher Genauigkeit und die Emotion der Schülerinnen und Schüler meist mit geringer Genauigkeit zu bewerten. Die Urteilsgenauigkeit der Lehrpersonen war sehr stabil mit nur geringen Veränderungen an den verschiedenen Genauigkeitskomponenten. Es kann gefolgert werden, dass chinesische Grundschullehrkräfte in der Lage sind, zu verschiedenen Zeitpunkten faire Urteile über Schülerleistungen und der Motivation ihrer Schülerinnen und Schüler zu treffen. Die Emotionen der Schülerinnen und Schüler sind für Lehrpersonen jedoch schwer zu erfassen. KW - Lehrer KW - Schülerbeurteilung KW - Schulleistungsmessung KW - Urteilsfähigkeit Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-7387 ER - TY - CHAP A1 - Parra Rodriguez, Juan D. A1 - Posegga, Joachim T1 - RAPID: Resource and API-Based Detection Against In-Browser Miners T2 - Proceedings of the 34th Annual Computer Security Applications Conference N2 - Direct access to the system's resources such as the GPU, persistent storage and networking has enabled in-browser crypto-mining. Thus, there has been a massive response by rogue actors who abuse browsers for mining without the user's consent. This trend has grown steadily for the last months until this practice, i.e., CryptoJacking, has been acknowledged as the number one security threat by several antivirus companies. Considering this, and the fact that these attacks do not behave as JavaScript malware or other Web attacks, we propose and evaluate several approaches to detect in-browser mining. To this end, we collect information from the top 330.500 Alexa sites. Mainly, we used real-life browsers to visit sites while monitoring resource-related API calls and the browser's resource consumption, e.g., CPU. Our detection mechanisms are based on dynamic monitoring, so they are resistant to JavaScript obfuscation. Furthermore, our detection techniques can generalize well and classify previously unseen samples with up to 99.99\% precision and recall for the benign class and up to 96\% precision and recall for the mining class. These results demonstrate the applicability of detection mechanisms as a server-side approach, e.g., to support the enhancement of existing blacklists. Last but not least, we evaluated the feasibility of deploying prototypical implementations of some detection mechanisms directly on the browser. Specifically, we measured the impact of in-browser API monitoring on page-loading time and performed micro-benchmarks for the execution of some classifiers directly within the browser. In this regard, we ascertain that, even though there are engineering challenges to overcome, it is feasible and beneficial for users to bring the mining detection to the browser. KW - Web Security KW - WebRTC KW - postMessage KW - Browser Security KW - Content Security Policy Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-6550 SN - 978-1-4503-6569-7 PB - ACM CY - New York, NY, USA ER - TY - CHAP A1 - Parra Rodriguez, Juan D. A1 - Schreckling, Daniel A1 - Posegga, Joachim T1 - Addressing Data-Centric Security Requirements for IoT-Based Systems T2 - 2016 International Workshop on Secure Internet of Things (SIoT) N2 - Allowing users to control access to their data is paramount for the success of the Internet of Things; therefore, it is imperative to ensure it, even when data has left the users' control, e.g. shared with cloud infrastructure. Consequently, we propose several state of the art mechanisms from the security and privacy research fields to cope with this requirement. To illustrate how each mechanism can be applied, we derive a data-centric architecture providing access control and privacy guaranties for the users of IoT-based applications. Moreover, we discuss the limitations and challenges related to applying the selected mechanisms to ensure access control remotely. Also, we validate our architecture by showing how it empowers users to control access to their health data in a quantified self use case. KW - Internet of Things KW - Security Architecture KW - Data-Centric Security KW - Differential Privacy KW - Secure Cloud Storage Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-6546 SN - 978-1-5090-5091-8 PB - IEEE Xplore CY - Heraklion, Greece ER - TY - CHAP A1 - Parra Rodriguez, Juan D. A1 - Posegga, Joachim T1 - Local Storage on Steroids: Abusing Web Browsers for Hidden Content Storage and Distribution T2 - International Conference on Security and Privacy in Communication Systems N2 - Analysing security assumptions taken for the WebRTC and postMessage APIs led us to find a novel attack abusing the browsers' persistent storage capabilities. The presented attack can be executed without the website's visitor knowledge, and it requires neither browser vulnerabilities nor additional software on the browser's side. To exemplify this, we study how can an attacker use browsers to create a network for persistent storage and distribution of arbitrary data. In our proof of concept, the total storage of the network, and therefore the space used within each browser, grows linearly with the number of origins delivering the malicious JavaScript code. Further, data transfers between browsers are not restricted by the Same Origin Policy, which allows for a unified cross-origin browser network, regardless of the origin from which the script executing the functionality is loaded from. In the course of our work, we assess the feasibility of a real-life deployment of the network by running experiments using Linux containers and browser automation tools. Moreover, we show how security mechanisms against third-party tracking, cross-site scripting and click-jacking can diminish the attack's impact, or even prevent it. KW - Web Security KW - WebRTC KW - postMessage KW - Browser Security Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-6572 SN - 978-3-030-01704-0 PB - Springer CY - Cham ER - TY - CHAP A1 - Parra Rodriguez, Juan D. A1 - Posegga, Joachim T1 - CSP & Co. Can Save Us from a Rogue Cross-Origin Storage Browser Network! But for How Long? T2 - Proceedings of the Eighth ACM Conference on Data and Application Security and Privacy N2 - We introduce a new browser abuse scenario where an attacker uses local storage capabilities without the website's visitor knowledge to create a network of browsers for persistent storage and distribution of arbitrary data. We describe how security-aware users can use mechanisms such as the Content Security Policy (CSP), sandboxing, and third-party tracking protection, i.e., CSP & Company, to limit the network's effectiveness. From another point of view, we also show that the upcoming Suborigin standard can inadvertently thwart existing countermeasures, if it is adopted. KW - Web Security KW - WebRTC KW - PostMessage KW - Browser Security KW - Parasitic Computing Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-6561 SN - 978-1-4503-5632-9 PB - ACM CY - New York, NY, USA ER -