Positive association of relevant characteristics is a widespread pattern among adolescent friends. A positive association may be caused by the selection of similar others as friends and by the ...deselection of dissimilar ones, but also by influence processes where friends adjust their behavior to each other. Social control theory argues that adolescents select each other as friends based on delinquency. Differential association theory, on the other hand, argues that adolescent friends influence each other's delinquency levels. We employ new statistical methods for assessing the empirical evidence for either process while controlling for the other process. These methods are based on ‘actor‐oriented’ stochastic simulation models. We analyze longitudinal data on friendship networks and delinquent behavior collected in four waves of 544 students in 21 first‐grade classrooms of Dutch secondary schools. Results indicate that adolescents select others as friends who have a similar level of delinquency compared with their own level. Estimates of the social influence parameters are not significant. The results are consistent with social control theory but provide no support for differential association theory.
This paper describes an empirical comparison of four specifications of the exponential family of random graph models (ERGM), distinguished by model specification (dyadic independence, Markov, partial ...conditional dependence) and, for the Markov model, by estimation method (Maximum Pseudolikelihood, Maximum Likelihood). This was done by reanalyzing 102 student networks in 57 junior high school classes. At the level of all classes combined, earlier substantive conclusions were supported by all specifications. However, the different specifications led to different conclusions for individual classes. PL produced unreliable estimates (when ML is regarded as the standard) and had more convergence problems than ML. Furthermore, the estimates of covariate effects were affected considerably by controlling for network structure, although the precise specification of the structural part (Markov or partial conditional dependence) mattered less.
Abstract We introduce a novel procedure to assess the goodness of fit in relational event models. Building on existing auxiliary variable approaches developed in network modelling, the procedure ...involves a comparison between statistics computed on observed relational event sequences and statistics calculated on event sequences simulated from the fitted model. We argue that the internal time structure of the relational mechanisms assumed to generate the observations under the model is an important aspect of the fit of a model to observed relational event sequences. We establish the empirical value of the proposed goodness of fit approach in an analysis of data that we collected on collaborative patient-referral relations among healthcare organizations. The illustrative case study that we develop reveals distinctive features of relational event models that have been ignored or overlooked in received empirical studies.
Many chronically ill older patients in the Netherlands have a combination of more than one chronic disease. There is therefore a need for self-management programs that address general management ...problems, rather than the problems related to a specific disease. The Chronic Disease Self-Management Program (CDSMP) seems to be very suitable for this purpose. In evaluations of the program that have been carried out in the United States and China, positive effects were found on self-management behaviour and health status. However, the program has not yet been evaluated in the Netherlands. Therefore, the aim of this study was to evaluate the short-term and longer-term effects of the program among chronically ill older people in the Netherlands. One hundred and thirty-nine people aged 59 or older, with a lung disease, a heart disease, diabetes, or arthritis were randomly assigned to an intervention group (CDSMP) or a control group (care-as-usual). Demographic data and data on self-efficacy, self-management behaviour and health status were collected at three measurement moments (baseline, after 6 weeks, and after 6 months). The patients who participated rated the program with a mean of 8.5 points (range 0–10), and only one dropped out. However, our study did not yield any evidence for the effectiveness of the CDSMP on self-efficacy, self-management behaviour or health status of older patients in the Netherlands. Because the patients who participated were very enthusiastic, which was also indicated by very high mean attendance (5.6 out of 6 sessions) and only one dropout, it seems too early to conclude that the program is not beneficial for these patients.
Bilateral trade agreements have proliferated rapidly within the last two decades, growing into a dense network of multiple ties between countries. The spread of preferential trade agreements (PTAs), ...however, is not uniform: some countries have signed a multitude of deals, while others remain much less involved. This article presents a longitudinal network analysis method to analyze the patterns of the formation of trade agreements, based on the mutual codetermination of network structure and agreement formation. The findings suggest that PTAs spread endogenously because of structural arbitrage effects in the network, and that they establish a hierarchy among countries. Rich countries form ties with each other and middle-income countries, who themselves create a horizontal layer of PTAs, but least-developed countries are left behind and do not form many ties. Supplanting the multilateral trade regime with preferential agreements therefore creates a system of highly asymmetrical relationships of weaker spokes around a few hubs.
We consider the specification of effects of numerical actor attributes, having an interval level of measurement, in statistical models for directed social networks. A fundamental mechanism is ...homophily or assortativity, where actors have a higher likelihood to be tied with others having similar values of the variable under study. But there are other mechanisms that may also play a role in how the attribute values of two actors influence the likelihood of a tie between them. We discuss three additional mechanisms: aspiration, the tendency to send more ties to others having high values; attachment conformity, sending more ties to others whose values are close to the “social norm”; and sociability, where those having higher values will tend to send more ties generally. These mechanisms may operate jointly, and then their effects will be confounded. We present a specification representing these effects simultaneously by a four-parameter quadratic function of the values of sender and receiver. Flexibility can be increased by a five-parameter extension. We argue that for numerical actor attributes having important effects on directed networks, these specifications may provide an improvement. An illustration is given of dependence of advice ties on academic grades, analyzed by the Stochastic Actor-oriented Model.
Longitudinal studies of criminal networks are rare yet necessary to assess the adaptation and recovery of criminal networks after disruptions. We study the structural and individual effects of law ...enforcement disruption on criminal networks using longitudinal data on two Dutch jihadi networks (n1 = 57; n2 = 26). We expect that actors in criminal networks under disruption seek security and to remain concealed as much as possible. We argue how the structural properties of networks as well as mechanisms operating at the actor level might change after a disruption. We used descriptive measures of network cohesion together with core-periphery model fit and modularity to analyse the structural changes in the networks. To obtain the actor-level tendencies, we used undirected stochastic actor oriented models. At the structural level, both networks display opposite tendencies – the larger one is becoming less cohesive after the disruption, whereas the smaller network counter-intuitively becomes structurally more cohesive. Despite the structural differences, the actor-level mechanisms are similar in both studied networks with actors being inclined towards triadic closure and reliance on pre-existing ties. Our study demonstrates the importance of considering the analytical levels of networks and actors by showing that a disruption may disrupt the network at the structural level, while triggering contradictory unintended consequences by increasing individual-level connectivity as in the case of our second network.
•Network structure and actor-level mechanisms in criminal networks changes after a disruption.•We analyse longitudinal data about two disrupted Dutch jihadi networks.•While the structure of network 1 was dismantled after the disruption, the cohesion of network 2 increased.•Te found triadic closure operating in both networks accompanied by pre-existing ties translation in network 1.
The aim of this study was to unravel the interrelatedness of friendship and help, and to examine the characteristics of friendship and help networks. The effects of mutual versus one‐sided help ...relations on friendship initiation and maintenance, and vice versa, were examined. Friendship and help networks were analyzed (N = 953 students; 41 classrooms; Mage = 12.7). The results illustrate that friendship and help networks show some similarities, but only partly overlap and have distinct characteristics. Longitudinal multiplex social network analyses showed that mutual help was important for the maintenance of friendship, but not for the initiation of friendship. Further, particularly mutual friendships provided a context in which help took place. Implications of these findings are discussed.
•This study examined the dynamics of reputational dislike among adolescents.•Adolescents with higher peer status tended to be perceived as disliked over time.•Friendship promotes the creation and ...maintenance of reputational dislike ties.•Adolescents tended to agree with their friends to perceive others as disliked.•More frequent Facebook users tended to be perceived as disliked over time.
In this study, we examined the dynamics of the perception of “dislike” ties (reputational dislike) among adolescents within the contexts of friendship, perceived popularity, substance use, and Facebook use. Survey data were collected from a longitudinal sample of 238 adolescents from the 11th and 12th grades in one California high school. We estimated stochastic actor-based network dynamic models, using reports of reputational dislike, friendships, and perceived popularity, to identify factors associated with the maintenance and generation reputational dislike ties. The results showed that high-status adolescents and more frequent Facebook users tended to become perceived as or stay disliked by their peers over time. There was a tendency for friendships to promote the creation and maintenance of reputational disliking but not vice versa. Adolescents tended to perceive others as disliked when their friends also perceived them as disliked. There was no evidence that either cigarette smoking or drinking alcohol affected reputational dislike dynamics. This study highlights the important role that the hierarchical peer system, online peer context, and friendships play in driving information diffusion of negative peer relations among adolescents.
We propose two complementary ways to deal with a nesting structure in the node set of a network—such a structure may be called a multilevel network, with a node set consisting of several groups. ...First, within‐group ties are distinguished from between‐group ties by considering them as two distinct but interrelated networks. Second, effects of nodal variables are differentiated according to the levels of the nesting structure, to prevent ecological fallacies. This is elaborated in a study of two repeated observations of a sociability network in seven villages in Senegal, analyzed using the Stochastic Actor‐oriented Model.
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