Konzeptueller und logischer Data-Warehouse-Entwurf     

Holger Schwarz 《Informatik - Forschung und Entwicklung》2004,18(2):53-67

Zusammenfassung. Im Data-Warehouse-Bereich gibt es sowohl auf der konzeptuellen als auch auf der logischen Ebene unterschiedliche Modellierungsansätze, deren Entwicklung sich in der Regel an typischen Fragestellungen aus dem Bereich des Online Analytical Processing (OLAP) orientierte. Daneben spielen aber auch andere Ansätze zur Analyse der Daten in einem Data Warehouse eine bedeutende Rolle. Ein wichtiger Vertreter ist Data Mining, mit dessen Hilfe bislang unbekannte Muster und Zusammenhänge in Daten identifiziert werden können. Im vorliegenden Artikel wird untersucht, inwieweit sich die in der Literatur vorgeschlagenen konzeptuellen Datenmodelle für ein Data Warehouse eignen, das OLAP- und Data-Mining-Analysen gleichermaßen unterstützt. Hierzu wird das COCOM-Modell, das auf den Modellierungsmöglichkeiten verschiedener publizierter Modelle aufbaut, vorgestellt und bewertet. Für das logische Schema eines Data Warehouse wird häufig ein sogenanntes Star-Schema oder ein Snowflake-Schema erstellt. Für diese und weitere Schematypen wird analysiert, welchen Einfluss die Wahl des logischen Schemas auf Anwendungen aus den Bereichen OLAP und Data Mining hat. Wichtige Kriterien sind hier unter anderem der Informationsgehalt und die Performanz. Insgesamt zeigt dieser Beitrag, dass das COCOM-Modell und das Star-Schema eine gute Grundlage für den integrierten Einsatz von OLAP und Data-Mining bilden.Eingegangen am 30. April 2002, Angenommen am 25. Juni 2003 CR Subject Classification: H.2.1, H.2.7, H.2.8  相似文献   

Mental health services in independent secondary boarding schools: The need for a model     

Thomas J. Van Hoof  Holger Hansen 《Psychology in the schools》1999,36(1):69-78

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Publish@rs: Where do you want to go tomorrow?     

Holger Silberberger  Marc Ziegler 《Publishing Research Quarterly》2000,16(3):29-38

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Microfluidic system for near-patient extraction and detection of miR-122 microRNA biomarker for drug-induced liver injury diagnostics     

Maïwenn Kersaudy-Kerhoas  Antonio Liga  Appan Roychoudhury  Marilena Stamouli  Rhiannon Grant  Damaso Sanchez Carrera  Holger Schulze  Witold Mielczarek  Wilna Oosthuyzen  Juan F. Quintana  Paul Dickinson  Amy H. Buck  Nicholas R. Leslie  Jurgen Haas  Till T. Bachmann  James W. Dear 《Biomicrofluidics》2022,16(2)

Drug-induced liver injury (DILI) results in over 100 000 hospital attendances per year in the UK alone and is a leading cause for the post-marketing withdrawal of new drugs, leading to significant financial losses. MicroRNA-122 (miR-122) has been proposed as a sensitive DILI marker although no commercial applications are available yet. Extracellular blood microRNAs (miRNAs) are promising clinical biomarkers but their measurement at point of care remains time-consuming, technically challenging, and expensive. For circulating miRNA to have an impact on healthcare, a key challenge to overcome is the development of rapid and reliable low-cost sample preparation. There is an acknowledged issue with miRNA stability in the presence of hemolysis and platelet activation, and no solution has been demonstrated for fast and robust extraction at the site of blood draw. Here, we report a novel microfluidic platform for the extraction of circulating miR-122 from blood enabled by a vertical approach and gravity-based bubble mixing. The performance of this disposable cartridge was verified by standard quantitative polymerase chain reaction analysis on extracted miR-122. The cartridge performed equivalently or better than standard bench extraction kits. The extraction cartridge was combined with electrochemical impedance spectroscopy to detect miR-122 as an initial proof-of-concept toward an application in point-of-care detection. This platform enables the standardization of sample preparation and the detection of miRNAs at the point of blood draw and in resource limited settings and could aid the introduction of miRNA-based assays into routine clinical practice.  相似文献   

A Nonlinear Structural Equation Mixture Modeling Approach for Nonnormally Distributed Latent Predictor Variables     

Augustin Kelava  Benjamin Nagengast  Holger Brandt 《Structural equation modeling》2013,20(3):468-481

Structural equation models with interaction and quadratic effects have become a standard tool for testing nonlinear hypotheses in the social sciences. Most of the current approaches assume normally distributed latent predictor variables. In this article, we describe a nonlinear structural equation mixture approach that integrates the strength of parametric approaches (specification of the nonlinear functional relationship) and the flexibility of semiparametric structural equation mixture approaches for approximating the nonnormality of latent predictor variables. In a comparative simulation study, the advantages of the proposed mixture procedure over contemporary approaches [Latent Moderated Structural Equations approach (LMS) and the extended unconstrained approach] are shown for varying degrees of skewness of the latent predictor variables. Whereas the conventional approaches show either biased parameter estimates or standard errors of the nonlinear effects, the proposed mixture approach provides unbiased estimates and standard errors. We present an empirical example from educational research. Guidelines for applications of the approaches and limitations are discussed.  相似文献   

On the Performance of Likelihood-Based Difference Tests in Nonlinear Structural Equation Models     

Carla Gerhard  Andreas G. Klein  Karin Schermelleh-Engel  Helfried Moosbrugger  Jana Gäde  Holger Brandt 《Structural equation modeling》2013,20(2):276-287

This article investigates likelihood-based difference statistics for testing nonlinear effects in structural equation modeling using the latent moderated structural equations (LMS) approach. In addition to the standard difference statistic T_D, 2 robust statistics have been developed in the literature to ensure valid results under the conditions of nonnormality or small sample sizes: the robust T_DR and the “strictly positive” T_DRP. These robust statistics have not been examined in combination with LMS yet. In 2 Monte Carlo studies we investigate the performance of these methods for testing quadratic or interaction effects subject to different sources of nonnormality, nonnormality due to the nonlinear terms, and nonnormality due to the distribution of the predictor variables. The results indicate that T_D is preferable to both T_DR and T_DRP. Under the condition of strong nonlinear effects and nonnormal predictors, T_DR often produced negative differences and T_DRP showed no desirable power.  相似文献   

The effect of school inspections on school improvement     

Holger Gaertner  Sebastian Wurster  Hans Anand Pant 《School Effectiveness & School Improvement》2013,24(4):489-508

This study uses a school-level longitudinal control-group design to examine how teachers and principals of inspected versus uninspected schools perceive school improvement at their schools. During the phasing in of school inspections in the states of Berlin and Brandenburg (Germany), both inspected and uninspected schools were surveyed with respect to school improvement activities over a 1-year period. The main finding is that principals’ and teachers’ perceptions of school quality were highly stable, irrespective of the introduction of school inspections. The results show school inspections had a comparatively low impact on the aspects of school quality measured here.  相似文献   

Wirtschaftliche Bedeutung des Sportkonsums in Deutschland     

Prof. Dr. Holger Preuß  Christian Alfs 《Sportwissenschaft》2013,43(4):239-252

The aim of this research project was to determine the volume and structure of the sport-related consumption (based on participation and on interest) of private households in Germany in the year 2010 in a differentiated and extensive way. A representative computer-assisted telephone interview (CATI) survey with n?=?7,031 was implemented, followed by a computer-assisted web interview (CAWI) survey with n?=?12,365. This way, data was gathered on the number of people spending money on sport and the respective amounts spent, differentiating between 48 sport-related categories of consumption. The results show that—in the realistic scenario—a total sum of 138.6 bn euros were spent, of which 112.6 bn euros were caused by participation and the remaining 26 bn euros alone by the interest in sport. The most relevant categories of participation-based consumption were transportation costs (33.7 bn euros; 30?% of the total), sport-related vacation and training camps (22.4 bn euros; 19.9?%) and shoes and clothing (15.3 bn euros; 13.3?%). The most relevant categories of interest-based sport consumption are entrance fees/tickets (10.4 bn euros; 40?% of the total), catering and accommodation (5.2 bn euros; 20.1?%) and media/information technology/pay TV (4 bn euros; 15.5?%).  相似文献   

Dynamics of mental model construction from text and graphics     

Ulrike Hochpöchler  Wolfgang Schnotz  Thorsten Rasch  Mark Ullrich  Holger Horz  Nele McElvany  Jürgen Baumert 《European Journal of Psychology of Education - EJPE》2013,28(4):1105-1126

When students read for learning, they frequently are required to integrate text and graphics information into coherent knowledge structures. The following study aimed at analyzing how students deal with texts and how they deal with graphics when they try to integrate the two sources of information. Furthermore, the study investigated differences between students from different school types and grades. Forty students from grades 5 and 8 from higher track and lower track of the German school system were asked to process and integrate texts and graphics in order to answer items from different levels of a text–picture integration taxonomy. Students’ eye movements were recorded and analyzed. Results suggest fundamentally different functions of text and graphics, which are associated with different processing strategies. Texts are more likely to be used according to a coherence-formation strategy, whereas graphics are more likely to be used on demand as visual cognitive tools according to an information-selection strategy. Students from different tracks of schooling revealed different adaptivity with regard to the requirements of combining text and graphic information.  相似文献   

The achievement flow motive as an element of the autotelic personality: predicting educational attainment in three cultures     

Holger Busch  Jan Hofer  Athanasios Chasiotis  Domingo Campos 《European Journal of Psychology of Education - EJPE》2013,28(2):239-254

Human behavior is directed by an implicit and an explicit motivational system. The intrinsic form of the implicit achievement motive has been demonstrated to predict the experience of flow. Thus, this achievement flow motive can be considered an integral component of the autotelic personality, posited in Flow Theory as dispositional difference in the propensity to experience flow. As implicit motivation predicts long-term behavioral trends and flow predicts quality of performance, the achievement flow motive should be predictive of a long-term goal pursuit such as educational attainment. This hypothesis is tested cross-culturally to shed some light on the universality of flow: Participants from Cameroon, Costa Rica, and Germany were asked about the level of education they attained. To assess their achievement flow motive, the Operant Motive Test was employed. After measurement equivalence was established, analyses revealed that, across all three cultures, the achievement flow motive explained variance in educational attainment independent of achievement values as measured by a scale of the Schwartz Value Survey. Consequently, as would be expected of an element of the autotelic personality, the achievement flow motive predicts long-term academic success.  相似文献