Robust designs for linear mixed effects models

Summary.  In health sciences, medicine and social sciences linear mixed effects models are often used to analyse time-structured data. The search for optimal designs for these models is often hampered by two problems. The first problem is that these designs are only locally optimal. The second problem is that an optimal design for one model may not be optimal for other models. In this paper the maximin principle is adopted to handle both problems, simultaneously. The maximin criterion is formulated by means of a relative efficiency measure, which gives an indication of how much efficiency is lost when the uncertainty about the models over a prior domain of parameters is taken into account. The procedure is illustrated by means of three growth studies. Results are presented for a vocabulary growth study from education, a bone gain study from medical research and an epidemiological decline in height study. It is shown that, for the mixed effects polynomial models that are applied to these studies, the maximin designs remain highly efficient for different sets of models and combinations of parameter values.     

Decision-Making in Agent-Based Models of Migration: State of the Art and Challenges

We review agent-based models (ABM) of human migration with respect to their decision-making rules. The most prominent behavioural theories used as decision rules are the random utility theory, as implemented in the discrete choice model, and the theory of planned behaviour. We identify the critical choices that must be made in developing an ABM, namely the modelling of decision processes and social networks. We also discuss two challenges that hamper the widespread use of ABM in the study of migration and, more broadly, demography and the social sciences: (a) the choice and the operationalisation of a behavioural theory (decision-making and social interaction) and (b) the selection of empirical evidence to validate the model. We offer advice on how these challenges might be overcome.     

Comparing Group and Individual Level Assessments of Job Characteristics in Testing the Job Demand-Control Model: A Multilevel Approach

This article describes a test of Karasek's JobDemand-Control (JD-C) Model using both group andindividual level assessments of job characteristics. Bygroup assessments, we mean aggregated individual data. A random sample from general hospitals andnursing homes included 16 institutions, 64 units, and1489 health care workers (82% response). Because of thehierarchically nested data structure (i.e.,institutions, units, and individuals) the research questionsand hypothesis were tested in multilevel regressionanalyses (VARCL). The results revealed both group leveland individual level effects with regard topsychological outcomes, and stressed the usefulness ofmultilevel techniques. Karasek's JD-C Model was partlyconfirmed by finding two interaction effects at grouplevel and at individual level with regard to jobsatisfaction and work motivation, respectively. Thediscussion focuses on theoretical, methodological, andpractical implications of multilevel modeling withrespect to the JD-C Model.     

Collective and Reflexive Styles of Volunteering: A Sociological Modernization Perspective

This paper presents a theory-guided examination of the (changing) nature of volunteering through the lens of sociological modernization theories. Existing accounts of qualitative changes in motivational bases and patterns of volunteering are interpreted against the background of broader, modernization-driven social-structural transformations. It is argued that volunteer involvement should be qualified as a biographically embedded reality, and a new analytical framework of collective and reflexive styles of volunteering is constructed along the lines of the ideal-typical biographical models that are delineated by modernization theorists. Styles of volunteering are understood as essentially multidimensional, multiform, and multilevel in nature. Both structural-behavioral and motivational-attitudinal volunteering features are explored along the lines of six different dimensions: the biographical frame of reference, the motivational structure, the course and intensity of commitment, the organizational environment, the choice of (field of) activity, and the relation to paid work.     

Self-evaluation of assessment programs: a cross-case analysis

The goal of this article is to contribute to the validation of a self-evaluation method, which can be used by schools to evaluate the quality of their Competence Assessment Program (CAP). The outcomes of the self-evaluations of two schools are systematically compared: a novice school with little experience in competence-based education and assessment, and an innovative school with extensive experience. The self-evaluation was based on 12 quality criteria for CAPs, including both validity and reliability, and criteria stressing the importance of the formative function of assessment, such as meaningfulness and educational consequences. In each school, teachers, management and examination board participated. Results show that the two schools use different approaches to assure assessment quality. The innovative school seems to be more aware of its own strengths and weaknesses, to have a more positive attitude towards teachers, students, and educational innovations, and to explicitly involve stakeholders (i.e., teachers, students, and the work field) in their assessments. This school also had a more explicit vision of the goal of competence-based education and could design its assessments in accordance with these goals.