Introduction

Structural equation models (SEMs) are used by biologists, educational researchers, market researchers, medical researchers, psychologists, social scientists, and others who traditionally deal with nonexperimental and quasi-experimental data. One reason for the pervasive use in almost every scientific field of study is that SEMs provide researchers with a comprehensive method for the quantification and testing of theories. In fact, it has been suggested that the development of SEM is perhaps the most important and influential statistical revolution to have recently occurred in the scientific arena (Cliff, 1983).