Path Diagrams: Layout Algorithms, Styles, and Views

Abstract

Path diagrams are valuable visualization tools in practical structural equation modeling (SEM). They provide intuitively appealing representations of modeling ideas and results. As a part of the computational process of modeling, path diagrams can be viewed as input device or as output results. This paper discusses the latter role of path diagrams. The modeling scenario of interest is to produce path diagrams given the syntactic input of structural models. The process-flow, grouped-flow, and GRIP layout algorithms for producing path diagrams are described and discussed. Emphases are on building intuitions about these layout algorithms and hence the appropriate use of these algorithms for producing path diagrams for different types of models. Steps that automate the selection among these layout algorithms for a given model are proposed. Finally, adjustments that are needed for producing path diagrams with different styles and views are discussed. Path diagram examples are used throughout the paper to illustrate the layout algorithms, the proposed automatic selection steps, and different styles and views.