A family of measures to evaluate scale reliability in a longitudinal setting

Summary.  The concept of reliability denotes one of the most important psychometric properties of a measurement scale. Reliability refers to the capacity of the scale to discriminate between subjects in a given population. In classical test theory, it is often estimated by using the intraclass correlation coefficient based on two replicate measurements. However, the modelling framework that is used in this theory is often too narrow when applied in practical situations. Generalizability theory has extended reliability theory to a much broader framework but is confronted with some limitations when applied in a longitudinal setting. We explore how the definition of reliability can be generalized to a setting where subjects are measured repeatedly over time. On the basis of four defining properties for the concept of reliability, we propose a family of reliability measures which circumscribes the area in which reliability measures should be sought. It is shown how different members assess different aspects of the problem and that the reliability of the instrument can depend on the way that it is used. The methodology is motivated by and illustrated on data from a clinical study on schizophrenia. On the basis of this study, we estimate and compare the reliabilities of two different rating scales to evaluate the severity of the disorder.     

Emancipation and Self-determination of People with Learning Disabilities and Down-sizing Institutional Care

In Arduin, an organisation for services to people with learning disabilities in the Netherlands, the emancipation and self-determination of people with learning disabilities has been positively adopted as fundamental in order to secure the best possible quality of life of the clients. The client is being encouraged in several ways in a development from a position of dependence towards self-determination. The services provided by the organisation had to be adjusted accordingly and are also going through a transition from 'providing a total care service' towards 'offering the support that the client desires'. In this article the background and developments in perception are being outlined, and those dimensions in quality of life are elaborated that are seen as most essential in the innovation: inclusion, self-determination and personal development. The choices that were made as a consequence in Arduin and most fundamental the choice to dismantle the institution are described.     

The role of crisis in family crisis intervention: Do crisis experience and crisis change matter?

Evaluation studies of crisis intervention have focused on prevention of out-of-home placement of children or family functioning, but largely neglected the aspect of crisis. The present study examined crisis in 183 families receiving Family Crisis Intervention (FCI), addressing crisis characteristics and crisis change. In questionnaires children and parents were asked about their definition and experience of crisis and about their need for help. Results show that all families but one were in crisis at the beginning of the intervention, although the perception and extent of crisis differed among respondents. Crisis decreased from baseline to posttest according to clients and crisis intervention workers, but was not absent after the intervention. Combined with an unexpected pattern of reported family balance in the months before FCI, this result challenges the 4-6 weeks time span assumption of a crisis period. Variations in perception of crisis, clients' need for help, and possible crisis patterns are discussed, addressing theoretical and practical implications for family crisis intervention.     

Validation of a longitudinally measured surrogate marker for a time-to-event endpoint

The objective of this paper is to extend the surrogate endpoint validation methodology proposed by Buyse et al. (2000) to the case of a longitudinally measured surrogate marker when the endpoint of interest is time to some key clinical event. A joint model for longitudinal and event time data is required. To this end, the model formulation of Henderson et al. (2000) is adopted. The methodology is applied to a set of two randomized clinical trials in advanced prostate cancer to evaluate the usefulness of prostate-specific antigen (PSA) level as a surrogate for survival.     

Asymptotic Variance of Semiparametric Estimators With Generated Regressors

We study the asymptotic distribution of three‐step estimators of a finite‐dimensional parameter vector where the second step consists of one or more nonparametric regressions on a regressor that is estimated in the first step. The first‐step estimator is either parametric or nonparametric. Using Newey's (1994) path‐derivative method, we derive the contribution of the first‐step estimator to the influence function. In this derivation, it is important to account for the dual role that the first‐step estimator plays in the second‐step nonparametric regression, that is, that of conditioning variable and that of argument.     

The impact of respondents and interviewers on interview speed in face-to-face interviews

In surveys carried out by interviewers trained according to the key principle of standardized interviewing it is assumed that the interviewer has only limited impact on the time a respondent needs to answer questions. In the paper the effects of interviewers and respondent characteristics on interview speed are analyzed simultaneously by means of a three-level random coefficient model. Data from the fifth round of the European Social Survey (ESS) are used. In twelve participating countries (CAPI) timers were implemented at several places in the questionnaire. Based on this time information the interview speed (number of questions asked per minute) was measured for each respondent during five modules of the questionnaire. The results support most of the expectations concerning the effects of the respondent characteristics. However, the results also indicate that, for all countries, interviewers strongly determine the interview speed and that interview length is not a simple linear function of the number of questions in a questionnaire.     

Visiting borders in education: A creative approach with children in primary education

This study engages with children sharing experiences of belonging at school, of receiving access and of exploring complex relationalities along shifting borders in educational spaces. Their understandings offer a magnifying glass on normativity, difference and social positions in school spaces. Through ‘flattening and folding’ with material and theoretical concepts, the authors map how qualitative data images made by children and theory constitute one another to make sense of complex relationalities discussed by children. The project desires to make sense of blurry borders that exclude children in educational contexts and to push borders in methods and ethics in research with children.     

Teamworking and organizational performance: A review of survey‐based research

This paper presents a review of recent survey‐based research looking at the contribution of teamwork to organizational performance. In particular, it focuses on empirical studies in which both teamwork and performance are directly measured in a quantitative way. The paper begins by identifying four interrelated dimensions of teamwork effectiveness: attitudinal, behavioural, operational and financial. The first two represent transmission mechanisms by which organizational performance can be improved. The latter two provide direct measures of organizational outcomes. The review shows that teamworking has a positive impact on all four dimensions of performance. It also reveals that, when teamwork is combined with structural change, performance can be further enhanced. The paper concludes by highlighting some important research gaps that future studies could address.     

Transformation of non positive semidefinite correlation matrices

In multivariate statistics, estimation of the covariance or correlation matrix is of crucial importance. Computational and other arguments often lead to the use of coordinate-dependent estimators, yielding matrices that are symmetric but not positive semidefinite. We briefly discuss existing methods, based on shrinking, for transforming such matrices into positive semidefinite matrices, A simple method based on eigenvalues is also considered. Taking into account the geometric structure of correlation matrices, a new method is proposed which uses techniques similar to those of multidimensional scaling.     

On the right track? Islamic schools in the Netherlands after an era of turmoil

The Netherlands currently has 43 Islamic primary schools. Each is fully subsidised by the government. Yet since the first school was established in 1988 Islamic schools have been confronted with obstacles by the Ministry of Education, bad press and increasingly strict state supervision. Under pressure to improve their image, since 2008 Dutch Islamic primary schools have turned their attention away from expanding their numbers and instead focussed on improving school quality. In this article we describe the various developments and draw upon large scale empirical research to demonstrate the present state of affairs both in terms of cognitive and non-cognitive pupil achievements. We argue that the present results offer reasons to be cautiously optimistic.