Information access and retrieval with hypermedia information systems

Students' success with interactive information systems (IIS) such as those found in many CD-ROM applications depends to large degree on their capacity accurately to choose and apply search strategies in response to information needs. IIS systems provide many ways to retrieve information, with some methods being more efficient and effective than others. The purpose of this study was to investigate the search strategies employed by novice users of an IIS system and to analyse the problems and issues that were impediments to successful use. A class of 12 year old students was instructed in the use of an electronic encyclopaedia. The students used the encyclopaedia as an information source for individual projects and on completion their information skills tested and analysed. The study found that students tended to employ inefficient search strategies and experienced difficulty in creating search requests for information related problems.     

The association of socio-economic factors with physical fitness and activity behaviours,spinal posture and retinal vessel parameters in first graders in urban Switzerland

Socio-economic status during childhood has been shown to be a strong predictor of adult health outcome. Therefore, we examined associations of parental educational level, household income and migrant background with physical fitness, spinal flexibility, spinal posture as well as retinal vessel diameters in children of an urban Swiss region. A total of 358 first graders of the Swiss canton Basel-Stadt (age: 7.3, SD: 0.4) were examined. Physical fitness (20 m shuttle run test, 20 m sprint, jumping sidewards and balancing backwards), spinal flexibility and spinal posture (MediMouse^®, Idiag, Fehraltdorf, Switzerland) and retinal microcirculation (Static Retinal Vessel Analyzer, Imedos Systems UG, Jena, Germany) were assessed. Parental education, household income, migrant background and activity behaviour were evaluated with a questionnaire. Parental education was associated with child aerobic fitness (P = 0.03) and screen time (P < 0.001). Household income was associated with jumping sidewards (P = 0.009), balancing backwards (P = 0.03) and sports club participation (P = 0.02). Migrant background was associated with BMI (P = 0.001), body fat (P = 0.03), aerobic fitness (P = 0.007), time spent playing outdoors (P < 0.001) and screen time (P < 0.001). For spinal flexibility and retinal vessel diameter, no associations were found (0.06 < P < 0.8). Low parental education, low household income and a migrant background are associated with poor physical fitness, higher BMI and body fat percentage and low-activity behaviour.     

Academic self-concept, interest, grades, and standardized test scores: reciprocal effects models of causal ordering

Reciprocal effects models of longitudinal data show that academic self-concept is both a cause and an effect of achievement. In this study this model was extended to juxtapose self-concept with academic interest. Based on longitudinal data from 2 nationally representative samples of German 7th-grade students (Study 1: N = 5,649, M age = 13.4; Study 2: N = 2,264, M age = 13.7 years), prior self-concept significantly affected subsequent math interest, school grades, and standardized test scores, whereas prior math interest had only a small effect on subsequent math self-concept. Despite stereotypic gender differences in means, linkages relating these constructs were invariant over gender. These results demonstrate the positive effects of academic self-concept on a variety of academic outcomes and integrate self-concept with the developmental motivation literature.     

An ensemble-based likelihood ratio approach for family-based genomic risk prediction

Objective

As one of the most popular designs used in genetic research, family-based design has been well recognized for its advantages, such as robustness against population stratification and admixture. With vast amounts of genetic data collected from family-based studies, there is a great interest in studying the role of genetic markers from the aspect of risk prediction. This study aims to develop a new statistical approach for family-based risk prediction analysis with an improved prediction accuracy compared with existing methods based on family history.

Methods

In this study, we propose an ensemble-based likelihood ratio (ELR) approach, Fam-ELR, for family-based genomic risk prediction. Fam-ELR incorporates a clustered receiver operating characteristic (ROC) curve method to consider correlations among family samples, and uses a computationally efficient tree-assembling procedure for variable selection and model building.

Results

Through simulations, Fam-ELR shows its robustness in various underlying disease models and pedigree structures, and attains better performance than two existing family-based risk prediction methods. In a real-data application to a family-based genome-wide dataset of conduct disorder, Fam-ELR demonstrates its ability to integrate potential risk predictors and interactions into the model for improved accuracy, especially on a genome-wide level.

Conclusions

By comparing existing approaches, such as genetic risk-score approach, Fam-ELR has the capacity of incorporating genetic variants with small or moderate marginal effects and their interactions into an improved risk prediction model. Therefore, it is a robust and useful approach for high-dimensional family-based risk prediction, especially on complex disease with unknown or less known disease etiology.

     

A Bayesian Approach for Estimating Multilevel Latent Contextual Models

In many applications of multilevel modeling, group-level (L2) variables for assessing group-level effects are generated by aggregating variables from a lower level (L1). However, the observed group mean might not be a reliable measure of the unobserved true group mean. In this article, we propose a Bayesian approach for estimating a multilevel latent contextual model that corrects for measurement error and sampling error (i.e., sampling only a small number of L1 units from a L2 unit) when estimating group-level effects of aggregated L1 variables. Two simulation studies were conducted to compare the Bayesian approach with the maximum likelihood approach implemented in Mplus. The Bayesian approach showed fewer estimation problems (e.g., inadmissible solutions) and more accurate estimates of the group-level effect than the maximum likelihood approach under problematic conditions (i.e., small number of groups, predictor variable with a small intraclass correlation). An application from educational psychology is used to illustrate the different estimation approaches.     

Trainees' perspectives on the assessment and self‐assessment of surgical skills

Self‐assessment is argued to be valuable educationally and is being advocated through policies for wider adoption within medical practice. However, students are often reluctant to self‐assess and little research has examined the reasons for this. This study explored the perceptions of trainees and postgraduates on assessment and self‐assessment of surgical skills. Data were collected through semi‐structured interviews conducted with six trainees and postgraduate students in Oral Surgery. They had previously been assessed, and self‐assessed themselves for the first time, while surgically removing a mandibular third molar tooth. Assessments were judged against both an objective checklist scale and a global rating scale. Eight themes were identified and trainees’ comments on these themes analysed. The themes identified were assessment and stress, pressure to over‐ or under‐score, the impact of self‐assessment on learning, reflection and performance, confidence and the necessity of preparation, acceptability of the scales and criteria used, feedback, and the acceptability of self‐assessment. In conclusion we need to instil in our trainees a culture whereby they feel capable of and comfortable making judgements about their own performance and giving and receiving constructive assessment from their peers.     

Der Zusammenhang des Migrantenanteils in Schulen mit der Lesekompetenz: Differenzierte Analysen der erweiterten Migrantenstichprobe von PISA 2003

Zusammenfassung  Im vorliegenden Beitrag wird der Frage empirisch nachgegangen, ob in Schulen der Anteil von Jugendlichen, deren Familien aus der ehemaligen Sowjetunion oder aus der Türkei zugewandert sind, einen eigenst?ndigen Effekt auf die individuelle Lesekompetenz hat. Die zugrunde liegende Datenbasis bildet eine Teilstichprobe von 14.169 Jugendlichen aus der erweiterten Stichprobe von PISA-E 2003. Die mehrebenenanalytischen Auswertungen zeigen, dass der Anteil von Jugendlichen, deren Familien aus der ehemaligen Sowjetunion stammen, unter Kontrolle einer Vielzahl von Individual- und Kompositionsmerkmalen keinen eigenst?ndigen Effekt auf die Lesekompetenz hat. Im Gegensatz dazu findet sich für den Anteil von Jugendlichen türkischer Herkunft ein signifikant negativer Zusammenhang mit der Leseleistung. Mit einem Leistungsnachteil von 22 Punkten auf der PISA-Skala ist der Effekt in Schulen, in denen der Anteil dieser Herkunftsgruppe an der Schülerschaft gr?βer als 40 Prozent ist, besonders ausgepr?gt. Die Annahme, dass der Effekt des Migrantenanteils auf die Leseleistung überwiegend über die Herkunftssprache der Jugendlichen vermittelt wird, lie? sich nicht best?tigen. ■ Anm.: Summary und Keywords wurden von Dr. Orr geliefert, müssen also nicht noch einmal überprüft werden! ■     

Extension Procedures for Confirmatory Factor Analysis

We present factor extension procedures for confirmatory factor analysis that provide estimates of the relations of common and unique factors with external variables that do not undergo factor analysis. We present identification strategies that build upon restrictions of the pattern of correlations between unique factors and external variables. The first restriction minimizes the sum of squared correlations between unique factors and external variables. This approach is similar to the traditional factor extension procedure. The second restriction minimizes the complexity of the pattern of external correlations of unique factors. This approach has similarities with the simple structure ideal imposed on most factor rotation strategies. The procedures are illustrated with a real data example that demonstrates their applicability to real-world research questions.