Structural Equation Modeling/Path Analysis

Path Analysis is the statistical technique used to examine causal relationships between two or more variables. It is based upon a linear equation system and was first developed by Sewall Wright in the 1930s for use in phylogenetic studies. Path Analysis was adopted by the social sciences in the 1960s and has been used with increasing frequency in the ecological literature since the 1970s. In ecological studies, path analysis is used mainly in the attempt to understand comparative strengths of direct and indirect relationships among a set of variables. In this way, path analysis is unique from other linear equation models: In path analysis mediated pathways (those acting through a mediating variable, i.e., “Y,” in the pathway X → Y → Z) can be examined. Pathways in path models represent hypotheses of researchers, and can never be statistically tested for directionality. Numerous articles deal with the use of path analysis in ecological studies (See Shipley 1997, 1999 and Everitt and Dunn 1991 [Section 14.8] for discussion of ecological applications and misuses of the technique).