The linear-algebraic structure of least squares

Regression Analysis

Valuing information from mesoscale forecasts

The development of meso-gamma scale numerical weather prediction (NWP) models requires a substantial investment in research, development and computational resources. Traditional objective verification of deterministic model output fails to demonstrate the added value of high-resolution forecasts made by such models. It is generally accepted from subjective verification that these models nevertheless have a predictive potential for small-scale weather phenomena and extreme weather events. This has prompted an extensive body of research into new verification techniques and scores aimed at developing mesoscale performance measures that objectively demonstrate the return on investment in meso-gamma NWP. In this article it is argued that the evaluation of the information in mesoscale forecasts should be essentially connected to the method that is used to extract this information from the direct model output (DMO). This could be an evaluation by a forecaster, but, given the probabilistic nature of small-scale weather, is more likely a form of statistical post-processing. Using model output statistics (MOS) and traditional verification scores, the potential of this approach is demonstrated both on an educational abstraction and a real world example. The MOS approach for this article incorporates concepts from fuzzy verification. This MOS approach objectively weighs different forecast quality measures and as such it is an essential extension of fuzzy methods

Direction-Projection-Permutation for High Dimensional Hypothesis Tests

Motivated by the prevalence of high dimensional low sample size datasets in modern statistical applications, we propose a general nonparametric framework, Direction-Projection-Permutation (DiProPerm), for testing high dimensional hypotheses. The method is aimed at rigorous testing of whether lower dimensional visual differences are statistically significant. Theoretical analysis under the non-classical asymptotic regime of dimension going to infinity for fixed sample size reveals that certain natural variations of DiProPerm can have very different behaviors. An empirical power study both confirms the theoretical results and suggests DiProPerm is a powerful test in many settings. Finally DiProPerm is applied to a high dimensional gene expression dataset

Auf alle Fälle ein Fall

Seit einigen Jahren, nicht zuletzt auch durch Studien wie PISA und TIMSS, kommt immer wieder die Forderung nach einer höheren Anwendungs- sowie Schülerinnen- und Schülerorientierung im Mathematikunterricht auf. Das Problembasierte Lernen (PBL) stellt einen Lehr-Lernansatz dar, der diesen Anforderungen begegnet und sich gleichzeitig für die Förderung verschiedener fachlicher und überfachlicher Kompetenzen in der Sekundarstufe und Hochschulbildung als geeignet herausgestellt hat. Entsprechende Konzepte für den Grundschulmathematikunterricht liegen bisher jedoch nicht vor. Dieser Beitrag widmet sich daher der Frage, wie eine Unterrichtskonzeption aufbauend auf PBL für den Mathematikunterricht der Grundschule gestaltet sein kann und welche Ziele mit dem Einsatz verfolgt werden. Dazu wird mithilfe der Methodologie des Design-Based Research (DBR) zunächst ein Konzept theoriebasiert ausgehend von PBL unter Einbezug allgemein- und fachdidaktischer Erkenntnisse entwickelt und dieses anschließend in der Praxis durch mehrere DBR-Zyklen erprobt sowie weiterentwickelt. Im vorliegenden Beitrag werden die ersten Phasen des DBR-Prozesses, welche auf die Entwicklung eines Prototyps abzielen, dargestellt, indem sich aus dem Problembasierten Lernen ergebende Grundideen identifiziert und daraus resultierende Merkmale für die Gestaltung der Konzeption generiert werden.Caused by studies such as PISA and TIMSS, the demand for a higher application and student orientation in mathematics classes has arisen in the recent past. Problem-based learning (PBL) as a teaching and learning approach is responsive to these requirements, while at the same time proving to be appropriate for the promotion of various subject-specific and generic competences in secondary and higher education. Corresponding concepts for mathematics classes in primary education are not yet available. Hence this article is devoted to the question, how a teaching concept, predicated on problem-based learning, can be designed for mathematics classes in primary schools and what goals can be pursued with its individual application. For this purpose, using the methodology of Design-Based Research (DBR), first a theory-based concept constitutive to PBL is developed by considering both, diverse subject related and general knowledge as well as results of research, which will then in practice be tested and developed further, employing several DBR cycles. In this article, the first phases of the DBR process, which focus on the development of a fundamental prototype, are presented by identifying basic ideas resulting from problem-based learning and generating resulting characteristics for the design of the concept

Epidemiology of Cerebral Palsy in the Netherlands

Children with cerebral palsy (CP) and their families often make strong demands on diagnostic, therapeutic, technical and social facilities. Prevalence estimates are needed to improve treatment and services. As recent Dutch data are not available, the present study aimed to assess the population prevalence of CP in the Netherlands. A representative Dutch area with 1.2 million inhabitants of which 172,000 were born between 1977 and 1988 was studied. To ascertain the children with CP from these birth years, medical practices (such as rehabilitation centres, paediatric and child neurological departments) were consecutively asked to contact their (supposed) CP cases. Next, a parents’ organisation and finally regional news media assisted in the ascertainment. In total, 170 ‘supposed’ CP cases underwent an expert examination. Of these 170, 127 children proved to be definite CP-cases, yielding a ‘crude’ average prevalence of 0.74 per 1000 inhabitants (95% CI: 0.61–0.87). Under-ascertainment was recognised and quantified. Accordingly, the population prevalence of CP over the birth year period 1977–1988 was calculated as 1.51 per 1000 inhabitants (average over the 12 birth years). The calculated CP prevalence rose significantly over time: from 0.77 (1977–1979) to 2.44 (1986–1988). This trend is in accordance with other studies

Nucleic Acid Lateral Flow Immunoassay for the Detection of Pathogenic Bacteria from Food

Nucleic acid lateral flow immunoassay (NALFIA) is a method combining molecular biological principle of detection with immunochemical principle of visualisation. Following isolation of DNA from the sample, a duplex PCR with two primer sets, of which one was labelled with biotin and the other with digoxigenin or fluorescein, respectively, was performed. The PCR solution and carbon particles conjugated with avidin are directly added to the nitrocellulose membrane with two test lines of immobilised antibodies specific for digoxigenin and fluorescein. The appearance of a black line indicates the presence of specific amplicon. We would like to present the NALFIA for the simultaneous detection of L. monocytogenes in particular and the genus Listeria in general, in food. Bacteria from the genus Listeria frequently contaminate a large variety of foods. Occurrence of Listeria strains in food may indicate errors in good hygienic and manufacturing practice, only L. monocytogenes is a significant human and animal pathogen responsible for the serious illness listeriosis. Conventional microbiological methods for L. monocytogenes detection are laborious and take several days to achieve a confirmed identification

Between vulnerability and resilience : a network analysis of fluctuations in cognitive risk and protective factors following remission from depression

Research exploring how cognitive risk- and protective factors relate following remission from internalizing disorders suggests a central role for resilience. However, it remains unclear what constitutes resilience in this context. Furthermore, previous studies have typically relied on cross-sectional data which do not allow to map the temporal dynamics of such relations. Using a seven-day experience sampling period in 85 remitted depressed patients, we examined the interplay between five transdiagnostic vulnerability- and protective factors in daily life. We present a temporal, contemporaneous, and a between-subjects network, providing an in-depth analysis of how these factors relate to daily life fluctuations in residual symptomatology. Furthermore, we test the role of positive affect as a main resilience factor. Resilience uniquely predicted all other factors over time (temporal network). Higher levels of resilience were related to less momentary use of rumination, more deployment of positive appraisal, and lower occurrence of residual symptoms (contemporaneous network). Participants scoring high on resilience mostly engaged in positive appraisal (between-subjects network). Similar structures were obtained when substituting self-reported resilience by positive affect. This highlights the importance of resilience, and in particular, positive affectivity, to cope with stressors following remission. This may be fostered by facilitating the use of positive appraisal.</p