What does he mean? First, he means that path analysis should be based on the user’s personal understanding of causal processes, reflected in the causal diagram. It cannot be reduced to mechanical routines, such as those laid out in statistics manuals. For Wright, drawing a path diagram is not a statistical exercise; it is an exercise in genetics, economics, psychology, or whatever the scientist’s own field of expertise is.
In other words, it ensures the person doing the research actually understands it :)
