Marijtje van Duijn

Friendship Networks Through Time: An Actor-Oriented Dynamic Statistical Network Model

We propose a class of actor-oriented statistical models for closed social networks in general, and friendship networks in particular. The models are random utility models developed within a rational choice framework. Based on social psychological and sociological theories about friendship, mathematical functions capturing expected utility of individual actors with respect to friendship are constructed. Expected utility also contains a random (unexplained) component. We assume that, given their restrictions and contact opportunities, individuals evaluate their utility functions and behave such that they maximize the expected amount of utility. The behavior under consideration is the expression of like and dislike (choice of friends). Theoretical mechanisms that are modelled are, e.g., the principle of diminishing returns, the tendency towards reciprocated choices, and the preference for friendship relations with similar others. Constraints imposed on individuals are, e.g., the structure of the existing network, and the distribution of personal characteristics over the respondents. The models are illustrated by means of a data-set collected among university freshmen at 7 points in time during 1994 and 1995.

Position in formal structure, personal characteristics and choices of advisors in a law firm: A logistic regression model for dyadic network data☆

This paper presents a statistical model for the analysis of binary sociometric choice data, the p2 model, which provides a flexible way for using explanatory variables to model network structure. It is applied to examine the influence of the formal structure of an organization on interactions among its members. It is shown to provide a general and precise method for addressing this substantive issue. We identify the respective effects of position in the formal structure (status, seniority, division of work and office membership) and selected personal characteristics of members of a corporate law firm on their choices of advisors. Flows of advice are shown to be consistently shaped by status games and the pecking order in the firm. Other dimensions help members in mitigating the effect of this strong rule. This approach ultimately provides more understanding of how members of such firms try to balance cooperation and competition in terms of access to and management of key resources.

Essays on item response theory

1 The Life of Georg Rasch as a Mathematician and as a Statistician.- 2 The Growing Family of Rasch Models.- 3 Gain Scores Revisited Under an IRT Perspective.- 4 Modeling Learning in Short-Term Learning Tests.- 5 An IRT Model for Multiple Raters.- 6 Conditional Independence and Differential Item Functioning in the Two-Parameter Logistic Model.- 7 Differential Item Functioning Depending on General Covariates.- 8 Statistical Tests for Differential Test Functioning in Raschs Model for Speed Tests.- 9 Expected Response Functions.- 10 A Logistic IRT Model for Decreasing and Increasing Item Characteristic Curves.- 11 Using Parameter Expansion to Improve the Performance of the EM Algorithm for Multidimensional IRT Population-Survey Models.- 12 Cross-Validating Item Parameter Estimation in Adaptive Testing.- 13 Imputation of Missing Scale Data with Item Response Models.- 14 On the Interplay Between Nonparametric and Parametric IRT, with Some Thoughts About the Future.- 15 Reversibility Revisited and Other Comparisons of Three Types of Polytomous IRT Models.- 16 Progress in NIRT Analysis of Polytomous Item Scores: Dilemmas and Practical Solutions.- 17 Two-Level Nonparametric Scaling for Dichotomous Data.- 18 The Circles of Our Minds: &&A Nonparametric IRT Model for the Circumplex.- 19 Using Resampling Methods to Produce an Improved DIMTEST Procedure.- 20 Person Fit Across Subgroups: An Achievement Testing Example.- 21 Single-Peaked or Monotone Tracelines? On the Choice of an IRT Model for Scaling Data.- 22 Outline of a Faceted Theory of Item Response Data.- Abbreviations.

Ethnic boundaries and personal choice. Assessing the influence of individual inclinations to choose intra-ethnic relationships on pupils’ networks

The existence of ethnic boundaries in 20 pupils’ networks is tested by comparing the proportion of intra-ethnic to inter-ethnic relationships, while controlling for the distribution of intra- and inter-ethnic dyads in pupils’ networks. Also, we tested if those boundaries are affected by the inclinations of network members in choosing intra-ethnic group relationships. We used the p2 model for each school network and combined these results in a two-step procedure. Our results supported the hypotheses.

Lonely but not alone: Emotional isolation and social isolation as two distinct dimensions of loneliness in older people

The unidimensional nature of the De Jong-Gierveld Loneliness Scale is investigated. The internal properties of the scale scores were studied using item response theory, supplemented by an external validity study. In line with the theory of relational loneliness, the results stress the significance of distinguishing between emotional loneliness and social loneliness.

Simulation for Statistical Inference in Dynamic Network Models

Actor-oriented models are proposed for the statistical analysis of longitudinal social network data. These models are implemented as simulation models, and the statistical evaluation is based on the method of moments and the Robbins-Monro process applied to computer simulation outcomes. In this approach, the calculations that are required for statistical inference are too complex to be carried out analytically, and therefore they are replaced by computer simulation.

What Is Special About Social Network Analysis

In a short introduction on social network analysis, the main characteristics of social network data as well as the main goals of social network analysis are described. An overview of statistical models for social network data is given, pointing at differences and similarities between the various model classes and introducing the most recent developments in social network modeling.

Internal and external validity of the experiences in close relationships questionnaire in an american and two dutch samples

Background and objectives: The Experiences in Close Relationships scale (ECR) is much used in adult attachment research. In this study we examined: the psychometric properties of the Dutch ECR in comparison with the original American ECR; the claim of orthogonality of its scales Avoidance and Anxiety; and a broader applicability of the ECR, because much research is restricted to psychology student samples. Methods: In Study 1 we investigated the ECRs internal structure by means of confirmative factor analysis in the American psychology student sample in which the ECR was originally validated. We compared these findings with the results of factor analyses in: a Dutch psychology student sample to test whether the Dutch translation yields comparable results; and a Dutch general population sample to evaluate the Supposed orthogonality and to determine a broader applicability of the ECR. In Study 2 we evaluated aspects of the external validity of the ECR. Results: Confirmative factor analysis supports the original two factor structure in both Dutch samples, although less clear in the population sample. As opposed to both student samples the scales correlate moderately in the population sample. Results support external validity of the ECR in both Dutch samples. Conclusions: Since the supposed orthogonality of the scales varies by sample, the internal validity of the (Dutch) ECR varies by sample as well, namely from satisfactorily (population) to adequate (students). The external validity of the Dutch ECR is compared to the American version adequate, suggesting a broader applicability.

Assessment of professional behaviour in undergraduate medical education: peer assessment enhances performance

Objectives  To examine whether peer assessment can enhance scores on professional behaviour, with the expectation that students who assess peers score more highly on professional behaviour than students who do not assess peers.

Patterns of Adjustment to Partner Loss in Old Age: The Widowhood Adaptation Longitudinal Study

The present longitudinal study aims to explain emotional and social loneliness experienced by older adults (N=99) during two-and-a-half years of widowhood. Utilization of multilevel analysis and a “visual” cluster analysis with prescribed classification criteria enabled us to search for average adaptational developments as well as individual variability in the adjustment process. Results were interpreted within the theory of mental incongruity. Adjustment to loneliness appears to develop along different individual-specific curves. About 30 percent of the bereaved had not adapted in two-and-a-half years to their loss in terms of emotional loneliness. Presence of favorable opportunities such as good health and high self-esteem as well as coping efforts like social behavior resulted in lower levels of emotional and social loneliness. It is concluded that the adjustment process among older bereaved does not exist. Moreover, including measures of cognitions and attitudes that are related to the relational needs and desires of widow(er)s may enlarge our knowledge of how older adults adapt to partner death.