ABSTRACT
This chapter begins by presenting an easy-to-follow flowchart depicting the general principles behind constructing command files for structural equation modeling (SEM) software. It introduces essential elements of the notation and syntax used in the EQS, LISREL, and Mplus programs. Each SEM program may be considered a separate language with specific syntax and rules that must be precisely followed. The syntax is used to communicate to the program all needed details about observed data and models of concern to the researcher. An input file in EQS is made up of various commands. A command is typically followed by several keywords, or subcommands, and can go on for several lines. Setting up the model definition commands involves: writing out the equations relating each dependent variable to its explanatory variables; determining the status of all variances of independent variables; and determining the status of the covariances for all independent variables.
