Improved Insight into and Prediction of Network Dynamics by Combining VAR and Dimension Reduction

To understand within-person psychological processes, one may fit VAR(1) models (or continuous-time variants thereof) to multivariate time series and display the VAR(1) coefficients as a network. This approach has two major problems. First, the contemporaneous correlations between the variables will frequently be substantial, yielding multicollinearity issues. In addition, the shared effects of the variables are not included in the network. Consequently, VAR(1) networks can be hard to interpret. Second, crossvalidation results show that the highly parametrized VAR(1) model is prone to overfitting. In this article, we compare the pros and cons of two potential solutions to both problems. The first is to impose a lasso penalty on the VAR(1) coefficients, setting some of them to zero. The second, which has not yet been pursued in psychological network analysis, uses principal component VAR(1) (termed PC-VAR(1)). In this approach, the variables are first reduced to a few principal components, which are rotated toward simple structure; then VAR(1) analysis (or a continuous-time analog) is applied to the rotated components. Reanalyzing the data of a single participant of the COGITO study, we show that PC-VAR(1) has the better predictive performance and that networks based on PC-VAR(1) clearly represent both the lagged and the contemporaneous variable relations.     

Modeling Interactions Between Latent Variables in Research on Type D Personality: A Monte Carlo Simulation and Clinical Study of Depression and Anxiety

Several approaches exist to model interactions between latent variables. However, it is unclear how these perform when item scores are skewed and ordinal. Research on Type D personality serves as a good case study for that matter. In Study 1, we fitted a multivariate interaction model to predict depression and anxiety with Type D personality, operationalized as an interaction between its two subcomponents negative affectivity (NA) and social inhibition (SI). We constructed this interaction according to four approaches: (1) sum score product; (2) single product indicator; (3) matched product indicators; and (4) latent moderated structural equations (LMS). In Study 2, we compared these interaction models in a simulation study by assessing for each method the bias and precision of the estimated interaction effect under varying conditions. In Study 1, all methods showed a significant Type D effect on both depression and anxiety, although this effect diminished after including the NA and SI quadratic effects. Study 2 showed that the LMS approach performed best with respect to minimizing bias and maximizing power, even when item scores were ordinal and skewed. However, when latent traits were skewed LMS resulted in more false-positive conclusions, while the Matched PI approach adequately controlled the false-positive rate.     

Evaluating Structural Equation Models for Categorical Outcomes: A New Test Statistic and a Practical Challenge of Interpretation

This research is concerned with two topics in assessing model fit for categorical data analysis. The first topic involves the application of a limited-information overall test, introduced in the item response theory literature, to structural equation modeling (SEM) of categorical outcome variables. Most popular SEM test statistics assess how well the model reproduces estimated polychoric correlations. In contrast, limited-information test statistics assess how well the underlying categorical data are reproduced. Here, the recently introduced C₂ statistic of Cai and Monroe (2014) is applied. The second topic concerns how the root mean square error of approximation (RMSEA) fit index can be affected by the number of categories in the outcome variable. This relationship creates challenges for interpreting RMSEA. While the two topics initially appear unrelated, they may conveniently be studied in tandem since RMSEA is based on an overall test statistic, such as C₂. The results are illustrated with an empirical application to data from a large-scale educational survey.     

Trait anxiety and trait anger measured by ecological momentary assessment and their correspondence with traditional trait questionnaires

Ecological momentary assessments (EMA) of anxiety and anger/hostility were obtained every 25–30 min over two 24-h periods, separated by a median of 6 months, from 165 employees at a university in the Northeast. We used a multilevel trait-state-error structural equation model to estimate: (1) the proportion of variance in EMA anxiety and anger/hostility attributable to stable trait-like individual differences; (2) the correspondence between these trait-like components of EMA anxiety and anger/hostility and traditional questionnaire measures of each construct; and (3) the test–retest correlation between two 24-h averages obtained several months apart. After adjustment for measurement error, more than half the total variance in EMA reports of anxiety and anger/hostility is attributable to stable trait-like individual differences; however, the trait-like component of each construct is only modestly correlated with questionnaire measures of that construct. The 6-month “test–retest” correlations of latent variables representing the true 24-h EMA average anxiety and average anger are quite high (r ? 0.83). This study represents the longest follow-up period over which EMA-based estimates of traits have been examined. The results suggest that although the trait component (individual differences) of EMA momentary ratings of anxiety and anger is larger than the state component, traditional self-report questionnaires of trait anxiety and anger correspond only weakly with EMA-defined traits.     

A phase-field model for deformation twinning

We propose a phase-field model for modeling microstructure evolution during deformation twinning. The order parameters are proportional to the shear strains defined in terms of twin plane orientations and twinning directions. Using a face-centered cubic Al as an example, the deformation energy as a function of shear strain is obtained using first-principle calculations. The gradient energy coefficients are fitted to the twin boundary energies along the twinning planes and to the dislocation core energies along the directions that are perpendicular to the twinning planes. The elastic strain energy of a twinned structure is included using the Khachaturyan's elastic theory. We simulated the twinning process and microstructure evolution under a number of fixed deformations and predicted the twinning plane orientations and microstructures.     

Post-Christendom,Post-Constantinian,Post-Christian … Does the Label Matter?

The demise of Christendom is of fundamental significance in understanding the present and future relationship between the churches and European culture. Attempts to develop post-Christendom perspectives are hindered by linguistic and conceptual confusion. This article explores misleading implications of the terms ‘post-Constantinian’ and ‘post-Christian’ and argues for the consistent use of the term ‘post-Christendom’. Use of the terms ‘Christendom’ and ‘post-Christendom’ has been criticised for failing to differentiate between different kinds of Church–state partnerships, some of which may be less problematic than others. This article acknowledges such historical differences but argues that there is an underlying ideological unity susceptible of being described and investigated under these labels. It argues further that attempts to promote a benign expression of Christendom as a possible future for Europe are unwise. It summarises the transitions occurring as Europe journeys beyond Christendom and argues for creative engagement with post-Christendom as an opportunity for ecclesial renewal.     

Investigating the relationship between employability and self-efficacy: A cross-lagged analysis

The construct of employability has been conceptually related to self-efficacy in different ways. Employability has sometimes been regarded as an equivalent to self-efficacy, or as a distinct but related phenomenon. Since the relationship between the two phenomena has not been subjected to empirical scrutiny, the aim of the present study is to analyze whether self-efficacy and employability are two distinct but related constructs, and if they are, to investigate the direction of their relationship. The data (N = 1730) were collected through a two-wave longitudinal survey with one year between each data collection (2005 and 2006). The results of confirmatory factor analysis showed that the measures of employability and self-efficacy were distinct from one another, within and over measurement points, indicating that these are related but separate constructs. The results of latent variable cross-lagged analysis showed that employability predicted subsequent self-efficacy, even after controlling for age, gender, educational level, and regional differences. Thus, employability is not an expression of efficacy beliefs, but rather, the strengthening of employability perceptions may have beneficial effects on more general efficacy beliefs.     

Travel behavior changes and responses to advanced traveler information in prolonged and large-scale network disruptions: A case study of west LRT line construction in the city of Calgary

The objective of this study was the investigation of travel behavioral effects of the reduction in traffic capacity resulting from the construction of the West LRT (Light Rail Transit) line in the city of Calgary, Alberta, Canada. Travelers’ responses to real-time information providing traffic updates and advisory detours due to lane/road closures were also examined. The West LRT alignment extends approximately 8.2 km from downtown into the city’s southwest. Many road closures took place in the vicinity of the LRT line construction zones, inducing significant delays to traffic. Data on travelers’ behavioral responses and responses to real-time information were obtained by conducting a survey on a sample of users of the main road affected by the construction. The survey also investigated the effects of West LRT line construction on drivers’ daily commutes, including increases in travel times, mode choices, alternate route choices, and selection of sources of information on traffic conditions. A significant change in the selection of transportation mode was caused by West LRT construction. Throughout the construction period, there was a decrease in the percentage of respondents who reported private vehicles as their first choice and an increase in the percentage of respondents who preferred public transit as their first and second choices. Radio was found to be the most preferred source for traffic updates and detour advice, followed by variable message signs (VMS). The findings of the en-route information model showed that driving experience, employment status, travel time and purpose, and desire for pre-trip information had significant effects on traveler’s rerouting decisions after getting en-route information through VMS. The results from this study are of interest for understanding behavioral changes for the purposes of traffic management, mitigation schemes and design of advanced traveler information systems in response to network disruptions.