Package: umg 0.6.1

umg: Unified Model Graphs for Statistical Models in Psychology

Constructs, validates, lays out, and renders Unified Model Graphs (UMG), a formal graphical grammar for statistical models in psychology. Vertices are typed by observability, support, and inferential role; edges distinguish stochastic, symmetric, deterministic, and mixing dependence; plates encode replication and hierarchy. Diagrams can be themed and rendered with base 'grid' graphics, with 'ggplot2', as 'TikZ' code, or as 'Graphviz' DOT, and can be constructed either from one-line motif builders for many model families or automatically from 'lavaan', 'lme4', 'mirt', 'blavaan', 'brms', 'OpenMx', and 'qgraph' model objects. A diagram can be inspected as a data frame, summarised, and exported back to 'lavaan' model syntax, making the model-diagram correspondence operational in both directions. Each diagram also exposes identification diagnostics (scaling checks, a graphical counting rule, and a d-separation reader) and generates the exploratory display scaffolds implied by the model-data duality. The notation builds on established results for graphical and structural equation models: plate notation follows Buntine (1994) <doi:10.1613/jair.62>; the counting rule and scaling checks follow Bollen (1989) <doi:10.1002/9781118619179>; and the independence reader implements the d-separation criterion of Geiger, Verma and Pearl (1990) <doi:10.1002/net.3230200504> through the equivalent ancestral graph criterion of Lauritzen, Dawid, Larsen and Leimer (1990) <doi:10.1002/net.3230200503>.

Authors:Hsiu-Ting Yu [aut, cre]