Some Esoteric Aspects of SEM That Its Practitioners Should Want to Know

The topic of this article is the interpretation of structural equation modeling (SEM) solutions. Its purpose is to augment structural modeling's metatheoretic resources while enhancing awareness of how problematic is the causal significance of SEM-parameter solutions. Part I focuses on the nonuniqueness and consequent dubious interpretability of loop pathweights in nonrecursive SEMs: Solutions for a nonrecursive SEM's open parameters are strongly indeterminate absent constraints that in most applications would be arbitrary. The generic indeterminacy is well known, but how severely this thwarts identification of a linear dynamic system's structural coefficients from synchronic (one-panel) data still seems inadequately appreciated. Part II introduces an efficient formalism for recognizing an important facet of lawful regularity—locus displacements—that is generally suppressed by the equations in which mathematical models are standardly written. (Preoccupation with SEM's matrix algebra and fit appraisal has masked the cognitive poverty with which SEM applications are prevailingly conceived.) Introduced here are some unfamiliar concepts that enable us to think about system structure more deeply than matrix equations can express. The Appendix attempts to incite some debate on how we can best conceptualize and exploit different levels (molar vs. molecular) of subject conception while appreciating that not all becauses are productive causes. It provides an overview of explanatory determinations comprising more than just production causality.