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#

4 Tracing Rules of Path Analysis

One of the greatest advantages of path diagrams is
their foundation upon standard rules for reading paths, called
``tracing rules,'' which yield the expected variances and covariances
among the variables in the diagram.
In this section we first describe the tracing rules for standardized
variables, following Wright's (1934, 1968)
development of the method, and then outline the rules for
unstandardized variables. Although nearly all path diagrams may be
traced using rules for unstandardized variables,^{}
we present path derivations for standardized and unstandardized
variables separately because the former are much easier to trace than
the latter, and because rules for unstandardized variables are fairly
simple generalizations of the principles used in tracing paths between
standardized variables. An excellent resource for learning tracing
rules is the program RAMPATH (McArdle and Boker, 1990), which has a
`draw_bridges' command that illustrates the rules for any model.

**Subsections**

** Next:** 1 Tracing Rules for
** Up:** 5 Path Analysis and
** Previous:** 3 Assumptions of Path
** Index**
Jeff Lessem
2002-03-21