# Reference needed: Who introduced the graphical representation of a SEM?

I am hoping somebody can provide a reference to the paper that provide the first graphical representation of a structural equation model (SEM) that follows the generally accepted conventions like this figure.

• I can't categorically state that this is the origin of graphical representations of SEMs but this Wiki link about path analysis, a precursor of SEMs, notes that they were developed by Sewell Wright, a geneticist, about 100 years ago. I would start a deeper investigation with his work as it cascades through the literature. en.wikipedia.org/wiki/Path_analysis_(statistics) Jun 20 '16 at 17:39