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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Score-Based Approaches to Heterogeneity in Psychological Models

Arnold, Manuel 30 May 2022 (has links)
Statistische Modelle menschlicher Kognition und Verhaltens stützen sich häufig auf aggregierte Daten und vernachlässigen dadurch oft Heterogenität in Form von Unterschieden zwischen Personen oder Gruppen. Die Nichtberücksichtigung vorliegender Heterogenität kann zu verzerrten Parameterschätzungen und zu falsch positiven oder falsch negativen Tests führen. Häufig kann Heterogenität mithilfe von Kovariaten erkannt und vorhergesagt werden. Allerdings erweist sich die Identifizierung von Prädiktoren von Heterogenität oft als schwierige Aufgabe. Zur Lösung dieses Problems schlage ich zwei neue Ansätze vor, um individuelle und gruppenspezifische Unterschiede mithilfe von Kovariaten vorherzusagen. Die vorliegende kumulative Dissertation setzt sich aus drei Projekten zusammen. Projekt 1 widmet sich dem Verfahren IPC-Regression (Individual Parameter Contribution), welches die Exploration von Parameterheterogenität in Strukturgleichungsmodellen (SEM) mittels Kovariaten erlaubt. Unter anderem evaluiere ich IPC-Regression für dynamische Panel-Modelle, schlage eine alternative Schätzmethode vor und leite IPCs für allgemeine Maximum-Likelihood-Schätzer her. Projekt 2 veranschaulicht, wie IPC-Regression in der Praxis eingesetzt werden kann. Dazu führe ich schrittweise in die Implementierung von IPC-Regression im ipcr-Paket für die statistische Programmiersprache R ein. Schließlich werden in Projekt 3 SEM-Trees weiterentwickelt. SEM-Trees sind eine modellbasierte rekursive Partitionierungsmethode zur Identifizierung von Kovariaten, die Gruppenunterschiede in SEM-Parametern vorhersagen. Die bisher verwendeten SEM-Trees sind sehr rechenaufwendig. In Projekt 3 kombiniere ich SEM-Trees mit unterschiedlichen Score-basierten Tests. Die daraus resultierenden Score-Guided-SEM-Tees lassen sich deutlich schneller als herkömmlichen SEM-Trees berechnen und zeigen bessere statistische Eigenschaften. / Statistical models of human cognition and behavior often rely on aggregated data and may fail to consider heterogeneity, that is, differences across individuals or groups. If overlooked, heterogeneity can bias parameter estimates and may lead to false-positive or false-negative findings. Often, heterogeneity can be detected and predicted with the help of covariates. However, identifying predictors of heterogeneity can be a challenging task. To solve this issue, I propose two novel approaches for detecting and predicting individual and group differences with covariates. This cumulative dissertation is composed of three projects. Project 1 advances the individual parameter contribution (IPC) regression framework, which allows studying heterogeneity in structural equation model (SEM) parameters by means of covariates. I evaluate the use of IPC regression for dynamic panel models, propose an alternative estimation technique, and derive IPCs for general maximum likelihood estimators. Project 2 illustrates how IPC regression can be used in practice. To this end, I provide a step-by-step introduction to the IPC regression implementation in the ipcr package for the R system for statistical computing. Finally, Project 3 progresses the SEM tree framework. SEM trees are a model-based recursive partitioning method for finding covariates that predict group differences in SEM parameters. Unfortunately, the original SEM tree implementation is computationally demanding. As a solution to this problem, I combine SEM trees with a family of score-based tests. The resulting score-guided SEM trees compute quickly, solving the runtime issues of the original SEM trees, and show favorable statistical properties.
2

Individual differences in face cognition

Herzmann, Grit 28 July 2008 (has links)
Zusammenhänge zwischen neurokognitiven Indikatoren und Verhaltensindikatoren der Gesichterkognition können Gehirnsysteme und neuronale Subprozesse identifizieren, die individuellen Unterschieden im Verhalten zugrunde liegen. Diese Dissertation zeigt, dass Ereigniskorrelierte Potentiale (EKPs) als neurokognitive Indikatoren für die Erforschung individueller Unterschiede eingesetzt werden können, denn sie weisen die gleichen hohen psychometrischen Qualitäten wie andere Fähigkeitsindikatoren auf und messen daher individuelle Unterschiede in der neuronalen Verarbeitung zuverlässig und stabil über die Zeit. Auf der Verhaltensebene wurden drei Teilfähigkeiten der Gesichterkognition etabliert: Gesichterwahrnehmung, Gesichtergedächtnis und Gesichtergeschwindigkeit. EKPs wurden in Strukturgleichungsmodellen verwendet, um den Beitrag neurokognitiver Indikatoren an individuellen Unterschieden dieser Gesichterkognitionsfähigkeiten zu schätzen. Für 85 Probanden wurden Beziehungen zwischen den Gesichterkognitionsfähigkeiten und der P100, N170, der sogenannten Differenz aufgrund des Gedächtnisses (Dm) und dem frühen sowie späten Wiederholungseffekt (ERE und LRE) etabliert. Spezifische Anteile individueller Unterschiede in der Gesichterkognition auf der Verhaltensebene wurden durch individuelle Unterschiede im Zeitverlauf der strukturellen Gesichteranalyse (N170 Latenz) sowie in der Reaktivierung von Repräsentationen gespeicherter Gesichtsstrukturen (ERE) als auch personen-spezifischen Wissens (LRE) erklärt. Keinen Anteil an individuellen Unterschieden erklärten hingegen frühe Wahrnehmungsprozesse (P100), die neuronale Aktivierung während der strukturellen Gesichteranalyse (N170 Amplitude) und Prozesse der Gedächtnisenkodierung von Gesichtern (Dm). Diese Ergebnisse zeigen, dass individuelle Unterschiede in der Gesichterkognition von der strukturellen Gesichteranalyse sowie von der Effizienz und Geschwindigkeit des Zugriffs auf Gedächtnisinhalte zu Gesichtern und Personen abhängt. / Individual differences in perceiving, learning, and recognizing faces were shown on the behavioral and neural level but were rarely related to one another. By determining relationships between behavioral and neurocognitive indicators of face cognition, brain systems and neural sub-processes can be identified that underlie individual variations on the behavioral level. The present dissertation laid the foundation for using event-related potentials (ERPs) as neurocognitive indicators in individual differences research. ERP components were shown to possess the same high psychometric qualities as behavioral ability measures and thus to measure individual differences of neural processing reliably and stably across time. On the behavioral level, three component abilities of face cognition were established: face perception, face memory, and the speed of face cognition. ERP components were used in structural equation models that estimated contributions of neurocognitive indicators to the individual differences in these face cognition abilities. Regression analysis was used to determine the contributions of P100, N170, the so called difference due to memory (Dm), as well as early and late repetition effects (ERE and LRE) to face cognition abilities in 85 participants. Certain amounts of variance in face cognition as seen on the behavioral level were accounted for by individual differences in the temporal dimension of structural encoding of a face (N170 latency) and in the re-activation of both stored facial structures (ERE) and person-identity information (LRE). In contrast, processes of early vision (P100), the neural activation of structural face encoding (N170 amplitude), and memory encoding of new faces (Dm) did not show any contribution to individual differences in face cognition. These findings show that individual differences in face cognition depend on the speed of structurally encoding faces and on the efficiency and speed of accessing face and person memory.
3

Informal Economic Activities / Informelle ökonomische Aktivitäten

Bühn, Andreas 26 July 2010 (has links) (PDF)
The dissertation “Informal Economic Activities” takes a comprehensive approach to the informal economy by studying traditional shadow economic activities, household DIY activities, and the smuggling of illegal and legal goods. Chapter 2 analyzes shadow economic and DIY activities and presents a dual estimation for the development of both types of informal economic activities in Germany from 1970 to 2005. It also considers the impact of German reunification on shadow economic and DIY activities and employs a proper estimate of domestic currency in circulation within Germany as an indicator variable for the shadow economy. Chapter 3 studies an informal economic activity that has attracted much attention recently: legal goods smuggling, or the illegal trade of otherwise legal goods. The main channel of this type of smuggling is the falsification of trade documents. By reporting false amounts of exports and/or imports to authorities smugglers, or trade misinvoicers, seek to avoid paying taxes and/or tariffs. Chapter 4 widens the analysis of smuggling to the smuggling of illegal goods and studies the smuggling of legal and illegal goods across the U.S.-Mexico border in order to improve the understanding of illegal trade. Studying the U.S.-Mexican case is particularly interesting as most illegal drugs and immigrants enter the United States via the Mexican border. The empirical analyses in the dissertation “Informal Economic Activities” are based on structural equation models (SEMs). The results demonstrate that the informal economy is significant and that growth of the informal economy is not exclusive to developing countries, although it is a more serious problem in these countries. Moreover, although the informal economy covers a wide range of rather diverse economic activities, the dissertation works out that a few similarities exist. These are important, especially for policymakers, in first understanding what drives informal economic activities and second designing appropriate policies to deter them.
4

Essays in Intangible Corporate Assets

Aksin-Sivrikaya, Sezen 28 May 2021 (has links)
In einer zunehmend vernetzten Welt befinden sich Unternehmen in einem komplexen Beziehungsgeflecht aus verschiedenen Akteuren. Dies stellt eine Herausforderung für die Existenz traditioneller Geschäftsmodelle dar, da Firmen sich mit Konkurrenz aus allen Richtungen auseinander setzen müssen. In einem solchen Geschäftsumfeld werden immaterielle Vermögenswerte zunehmend als Grundlage für Wettbewerbsvorteile angesehen. Die Dissertation untersucht den materiellen Nutzen immaterieller Vermögenswerte und konzentriert sich dabei insbesondere auf die Unternehmensreputation und deren Einflussfaktoren. Wir verwenden als Theorie den Ressourcen-basierten Ansatz des Unternehmens und leiten unsere Hypothesen aus der vorhandenen Literatur ab, insbesondere in den Bereichen Reputation, Führung, Stakeholder-, Legitimitäts- und Signaling-Theorie. Unsere Analysen sind auf Umfragen des Manager Magazins und „Gold Bee Corporate Responsibility Assessment System“ basiert. Bei der Durchführung der quantitativen Analyse verwenden wir Strukturgleichungsmodelle. Die Implikationen dieser Dissertation lassen darauf schließen, dass es einen Business Case für ein aktives Reputationsmanagement sowohl auf Unternehmensebene als auch auf individueller Ebene für Führungskräfte, vornehmlich für den CEO, gibt. Weiterhin ist eine hohe Reputation ein nachhaltiger Wettbewerbsvorteil, da sie die Wettbewerbsposition des Unternehmens gegenüber den Wettbewerbern stärkt und potentiell neuen Wettbewerbern den Markteintritt erschwert. In ähnlicher Weise kann eine hohe CEO-Reputation als Instrument der Risikoreduzierung in Krisenzeiten genutzt werden. Außerdem zeigen unsere Ergebnisse, dass die ausschließliche Einhaltung von Regeln und Regulierungen nicht mehr ausreichend ist. Damit die Stakeholder Fortschritte belohnen können, muss das Management CSR-Programme etablieren, die bei ihren Stakeholdern Resonanz finden, und darüberhinaus kontinuierlich über die CSR-Leistungen ihres Unternehmens berichten. / In a digital world, the very existence of traditional business models is challenged as firms face disruptive innovation and intense competition. In such a business environment, intangible assets are increasingly perceived as the basis of competitive advantage. This thesis explores tangible benefits of intangible assets, specifically focusing on corporate reputation and CSR reporting quality. We take a resource-based view (RBV) of the firm and derive our testable hypotheses from the extant literature mostly in reputation, leadership, stakeholder theory, legitimacy theory, and signaling theory. Our data is mainly drawn from surveys conducted by Manager Magazin and Gold Bee Corporate Responsibility Assessment System, which has been developed by the CSR Reporting Research Group at the WTO Guide CSR Development Center. In performing our calculations, we adopt a (generalized) structural equation modeling approach. In our work, we uncover antecedent processes behind reputations. Our results imply that there is a business case for active management of both corporate and individual reputations by illustrating the link between reputations and firm outcomes. We show that corporate reputation can be utilized as a tool to protect and defend competitive positions, which can also work as a deterrent for potential market entrants. We further show that individual reputations may act as a medium to mitigate negative news and improve stakeholder perceptions in times of crises. Our findings also indicate that nonfinancial metrics are gaining prevalence. We illustrate that mere compliance with rules and regulations does not suffice anymore since in order for stakeholders to reward social and environmental progress, companies need to partake in CSR programs that resonate with their stakeholders and properly communicate associated nonfinancial metrics, which in turn will help improve firm outcomes through boosting internal and external intangible assets.
5

Informal Economic Activities

Bühn, Andreas 15 June 2010 (has links)
The dissertation “Informal Economic Activities” takes a comprehensive approach to the informal economy by studying traditional shadow economic activities, household DIY activities, and the smuggling of illegal and legal goods. Chapter 2 analyzes shadow economic and DIY activities and presents a dual estimation for the development of both types of informal economic activities in Germany from 1970 to 2005. It also considers the impact of German reunification on shadow economic and DIY activities and employs a proper estimate of domestic currency in circulation within Germany as an indicator variable for the shadow economy. Chapter 3 studies an informal economic activity that has attracted much attention recently: legal goods smuggling, or the illegal trade of otherwise legal goods. The main channel of this type of smuggling is the falsification of trade documents. By reporting false amounts of exports and/or imports to authorities smugglers, or trade misinvoicers, seek to avoid paying taxes and/or tariffs. Chapter 4 widens the analysis of smuggling to the smuggling of illegal goods and studies the smuggling of legal and illegal goods across the U.S.-Mexico border in order to improve the understanding of illegal trade. Studying the U.S.-Mexican case is particularly interesting as most illegal drugs and immigrants enter the United States via the Mexican border. The empirical analyses in the dissertation “Informal Economic Activities” are based on structural equation models (SEMs). The results demonstrate that the informal economy is significant and that growth of the informal economy is not exclusive to developing countries, although it is a more serious problem in these countries. Moreover, although the informal economy covers a wide range of rather diverse economic activities, the dissertation works out that a few similarities exist. These are important, especially for policymakers, in first understanding what drives informal economic activities and second designing appropriate policies to deter them.

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