mgm: Estimating Time-Varying Mixed Graphical Models in High-Dimensional Data

We present the R-package mgm for the estimation of k-order Mixed Graphical Models (MGMs) and mixed Vector Autoregressive (mVAR) models in high-dimensional data. These are a useful extensions of graphical models for only one variable type, since data sets consisting of mixed types of variables (continuous, count, categorical) are ubiquitous. In addition, we allow to relax the stationarity assumption of both models by introducing time-varying versions MGMs and mVAR models based on a kernel weighting approach. Time-varying models offer a rich description of temporally evolving systems and allow to identify external influences on the model structure such as the impact of interventions. We provide the background of all implemented methods and provide fully reproducible examples that illustrate how to use the package

A Tutorial on Estimating Time-Varying Vector Autoregressive Models

Time series of individual subjects have become a common data type in psychological research. These data allow one to estimate models of within-subject dynamics, and thereby avoid the notorious problem of making within-subjects inferences from between-subjects data, and naturally address heterogeneity between subjects. A popular model for these data is the Vector Autoregressive (VAR) model, in which each variable is predicted as a linear function of all variables at previous time points. A key assumption of this model is that its parameters are constant (or stationary) across time. However, in many areas of psychological research time-varying parameters are plausible or even the subject of study. In this tutorial paper, we introduce methods to estimate time-varying VAR models based on splines and kernel-smoothing with/without regularization. We use simulations to evaluate the relative performance of all methods in scenarios typical in applied research, and discuss their strengths and weaknesses. Finally, we provide a step-by-step tutorial showing how to apply the discussed methods to an openly available time series of mood-related measurements

Choosing between AR(1) and VAR(1) models in typical psychological applications.

Time series of individual subjects have become a common data type in psychological research. The Vector Autoregressive (VAR) model, which predicts each variable by all variables including itself at previous time points, has become a popular modeling choice for these data. However, the number of observations in typical psychological applications is often small, which puts the reliability of VAR coefficients into question. In such situations it is possible that the simpler AR model, which only predicts each variable by itself at previous time points, is more appropriate. Bulteel et al. (2018) used empirical data to investigate in which situations the AR or VAR models are more appropriate and suggest a rule to choose between the two models in practice. We provide an extended analysis of these issues using a simulation study. This allows us to (1) directly investigate the relative performance of AR and VAR models in typical psychological applications, (2) show how the relative performance depends both on n and characteristics of the true model, (3) quantify the uncertainty in selecting between the two models, and (4) assess the relative performance of different model selection strategies. We thereby provide a more complete picture for applied researchers about when the VAR model is appropriate in typical psychological applications, and how to select between AR and VAR models in practice

Success of economic sanctions threats: coercion, information and commitment

This study examines when and why threats of economic sanctions lead to the successful extraction of policy concessions. Scholars identified three (not mutually exclusive) hypotheses that explain the success of sanction threats: (a) the coercive, (b) the informational and (c) the public commitment hypothesis. The underpinning mechanisms for the hypotheses are, respectively, the economic cost of sanctions, uncertainty about the resolve of the sender and domestic audience cost for issuing empty threats. In this study, we offer an empirical test of the three hypotheses on threats effectiveness. In addition, we assess how variation in the three mechanisms affects the effectiveness of threats relative to imposed sanctions. For the expected economic cost, we use the TIES data. To measure uncertainty, we generate a network of diplomatic relations, based on Formal Alliance data, utilizing methods from complex network theory. To assess public commitment, we use the democracy score based on the POLITY IV data. Our results show that the effectiveness of threats strongly increases in an economic cost to the target; however, threats become increasingly effective relative to imposed sanctions for lower uncertainty and higher domestic audience cost

Success of economic sanctions threats: coercion, information and commitment

This study examines when and why threats of economic sanctions lead to the successful extraction of policy concessions. Scholars identified three (not mutually exclusive) hypotheses that explain the success of sanction threats: (a) the coercive, (b) the informational and (c) the public commitment hypothesis. The underpinning mechanisms for the hypotheses are, respectively, the economic cost of sanctions, uncertainty about the resolve of the sender and domestic audience cost for issuing empty threats. In this study, we offer an empirical test of the three hypotheses on threats effectiveness. In addition, we assess how variation in the three mechanisms affects the effectiveness of threats relative to imposed sanctions. For the expected economic cost, we use the TIES data. To measure uncertainty, we generate a network of diplomatic relations, based on Formal Alliance data, utilizing methods from complex network theory. To assess public commitment, we use the democracy score based on the POLITY IV data. Our results show that the effectiveness of threats strongly increases in an economic cost to the target; however, threats become increasingly effective relative to imposed sanctions for lower uncertainty and higher domestic audience cost

The network structure of schema modes

A fundamental question in psychotherapy is whether interventions should target client problems (i.e., problem-focused approaches) or client strengths (i.e., strength-focused approaches). In this study, we first propose to address this question from a network perspective on schema modes (i.e., healthy or dysfunctional patterns of co-occurring emotions, cognitions, and behaviours). From this perspective, schema modes mutually influence each other (e.g., healthy modes reduce dysfunctional modes). Recent evidence suggests that changes in modes that are strongly associated to other modes (i.e., central modes) could be associated with greater treatment effects. We therefore suggest research should investigate the relative centrality of healthy and dysfunctional modes. To make an exploratory start, we investigated the cross-sectional network structure of schema modes in a clinical (comprising individuals diagnosed with paranoid, narcissistic, histrionic, and Cluster C personality disorders) and non-clinical sample. Results showed that, in both samples, the Healthy Adult was significantly less central than several dysfunctional modes (e.g., Undisciplined Child and Abandoned and Abused Child). Although our study cannot draw causal conclusions, this finding could suggest that weakening dysfunctional modes (compared to strengthening the Healthy Adult) might be more effective in decreasing other dysfunctional modes. Our study further indicates that several schema modes are negatively associated, which could suggest that decreasing one might increase another. Finally, the Healthy Adult was among the modes that most strongly discriminated between clinical and non-clinical individuals. Longitudinal and experimental research into the network structure of schema modes is required to further clarify the relative influence of schema modes

The network structure of schema modes

A fundamental question in psychotherapy is whether interventions should target client problems (i.e., problem-focused approaches) or client strengths (i.e., strength-focused approaches). In this study, we first propose to address this question from a network perspective on schema modes (i.e., healthy or dysfunctional patterns of co-occurring emotions, cognitions, and behaviours). From this perspective, schema modes mutually influence each other (e.g., healthy modes reduce dysfunctional modes). Recent evidence suggests that changes in modes that are strongly associated to other modes (i.e., central modes) could be associated with greater treatment effects. We therefore suggest research should investigate the relative centrality of healthy and dysfunctional modes. To make an exploratory start, we investigated the cross-sectional network structure of schema modes in a clinical (comprising individuals diagnosed with paranoid, narcissistic, histrionic, and Cluster C personality disorders) and non-clinical sample. Results showed that, in both samples, the Healthy Adult was significantly less central than several dysfunctional modes (e.g., Undisciplined Child and Abandoned and Abused Child). Although our study cannot draw causal conclusions, this finding could suggest that weakening dysfunctional modes (compared to strengthening the Healthy Adult) might be more effective in decreasing other dysfunctional modes. Our study further indicates that several schema modes are negatively associated, which could suggest that decreasing one might increase another. Finally, the Healthy Adult was among the modes that most strongly discriminated between clinical and non-clinical individuals. Longitudinal and experimental research into the network structure of schema modes is required to further clarify the relative influence of schema modes

Registered Reports for Student Research

<p class="p1">The pre-registration of research via registered reports is a recent development in the field of psychology. The aim of pre-registration is to encourage research that presents sound hypotheses and methodology (Chambers, 2014) in order to counter undesirable but prevalent research practices such as cherry-picking and p-hacking. In this Letter from the Editors, we wish to echo calls for registered reports and outline how we, the Editors at the Journal of European Psychology Students (JEPS), plan to introduce registered reports for student research. We address the issues necessitating the introduction of registered reports and outline the approach needed for implementing this initiative in a student journal