Dr. Wolfgang Widermann
College of Education
University of Missouri
Wolfgang Wiedermann is an Associate Professor at the University of Missouri-Columbia. His primary research interests include the development of methods for causal inference, methods to determine the causal direction of dependence in observational data, and methods for person-oriented research settings. He has edited several books on new developments in statistical methods and published his work in top tier journals. He currently serves as an associate editor for Behaviormetrika and the Journal for Person-Oriented Research.
Direction Dependence Analysis: A Statistical Framework to Test the Causal Direction of Effects in Observational Data
Direction dependence analysis (DDA; www.ddaproject.com) is a recently proposed statistical framework that addresses the need for more sophisticated tools to evaluate causal mechanisms. In observational data settings, at least three possible explanations exist for the association of two variables x and y: 1) x is the cause of y (Model I), 2) y is the cause of x (Model II), or 3) an unmeasured confounder is present (Model III). DDA makes use of non-normality of variables to detect potential confounding and to probe the causal direction of linear variable relations. The “true” predictor is assumed to be a continuous non-normal exogenous variable. DDA involves the evaluation of three properties of the data: 1) observed distributions of the variables, 2) residual distributions of competing models, and 3) independence properties of predictors and residuals of competing models. Under non-normality, DDA components can be used to uniquely identify each explanatory model (Models I – III). Statistical inference methods for model selection are presented and implementations of DDA in SPSS and R are provided. The application of DDA is illustrated in the context of identifying mediators of a classroom behavior management training program on student academic competence (Wiedermann et al., 2020). The study involved a group randomized controlled trial with 105 teachers and 1818 students (K-3rd grade) in a large urban school district. DDA suggests that only student prosocial skill development causally mediated the intervention effects on student academic competence. Limitations and potential future directions of direction dependence modeling are discussed.