The Gaussian graphical model in cross-sectional and time-series data

We discuss the Gaussian graphical model (GGM; an undirected network of partial correlation coefficients) and detail its utility as an exploratory data analysis tool. The GGM shows which variables predict one-another, allows for sparse modeling of covariance structures, and may highlight potential causal relationships between observed variables. We describe the utility in 3 kinds of psychological datasets: datasets in which consecutive cases are assumed independent (e.g., cross-sectional data), temporally ordered datasets (e.g., n = 1 time series), and a mixture of the 2 (e.g., n > 1 time series). In time-series analysis, the GGM can be used to model the residual structure of a vector-autoregression analysis (VAR), also termed graphical VAR. Two network models can then be obtained: a temporal network and a contemporaneous network. When analyzing data from multiple subjects, a GGM can also be formed on the covariance structure of stationary means---the between-subjects network. We discuss the interpretation of these models and propose estimation methods to obtain these networks, which we implement in the R packages graphicalVAR and mlVAR. The methods are showcased in two empirical examples, and simulation studies on these methods are included in the supplementary materials.Comment: Accepted pending revision in Multivariate Behavioral Researc

Network psychometrics

In recent years, research on dynamical systems in psychology has emerged, which is analogous to other fields such as biology and physics. One popular and promising line of research involves the modeling of psychological systems as causal systems or networks of cellular automat. The general hypothesis is that noticeable macroscopic behavior—the co-occurrence of aspects of psychology such as cognitive abilities, psychopathological symptoms, or behavior—is not due to the influence of unobserved common causes, such as general intelligence, psychopathological disorders, or personality traits, but rather to emergent behavior in a network of interacting psychological, sociological, biological, and other components. This dissertation concerns the estimation of such psychological networks from datasets. While this line of research originated from a dynamical systems perspective, the developed methods have shown strong utility as exploratory data analysis tools, highlighting unique variance between variables rather than shared variance across variables (e.g., factor analysis). In addition, this dissertation shows that network modeling and latent variable modeling are closely related and can complement one-another. The methods are thus widely applicable in diverse fields of psychological research. To this end, the dissertation is split in three parts. Part I is aimed at empirical researchers with an emphasis on clinical psychology, and introduces the methods in conceptual terms and tutorials. Part II is aimed at psychometricians and methodologists, and discusses the methods in technical terms. Finally, Part III is aimed at R users with an emphasis on personality research

Witnessing and re-enacting in Cambodia: reflection on shifting testimonies

Thirty years after the collapse of the Khmer Rouge regime (1975-1979) how do Cambodians cope with the traumatic legacy of Pol Pot's reign of terror? What forms does witnessing take on in post-socialist and transitional Cambodia as senior Khmer Rouge leaders await prosecution at the Cambodian Tribunal? The paper examines aspects of witnessing in today's Cambodia, expressing each in its own way the idea of the 'shifting' of witnessing: the transformation of testimonies due to time passing and contrasted systems of justice through a comparison of testimonies in the trial of the 'Pol Pot/Ieng Sary clique' (1979) and the current Cambodian Tribunal; the complex forms of witnessing emerging from participatory projects developed with Western authors in 'We want (u) to know' (documentary movie made by an international film crew with the inhabitants of the village of Thnol Lok in 2009) and 'Breaking the silence' (theatre play realised by the Dutch dramaturge Annemarie Prins that premiered in Phnom Penh in 2009 and toured Cambodia in the following years); the relationship between documentary and legal forms of witnessing through the example of Vann Nath, a survivor of S-21/Tuol Sleng, the prison where the Khmer Rouge tortured and killed thousands of their fellow countrymen. The paper analyses the difficulty Western organisers of participatory projects experienced in applying the hybrid model of transitional justice to sociocultural contexts of witnessing. Nevertheless it points out their contribution to processes of 'recognition beyond recognition' in which cultural differences in coming to terms with historical trauma are expressed and recorded