Factor analysis is a widely used method for situations in which a small set of unobserved (latent) variables is believed to underlie a larger set of observed (manifest) variables. Exploratory factor analysis, available in most general statistics packages, is a technique for identifying structure in data and generating hypotheses. Confirmatory factor analysis differs in that it is much more theory driven and is generally used to test explicit hypotheses.

Confirmatory factor analysis is the basis of the measurement model in full structural equation modeling (SEM) and can be estimated using SEM software. Three SEM programs supported by Indiana University are Amos, LISREL, and Mplus. Of these, Amos and LISREL are the most user-friendly, although Mplus syntax is not at all difficult to learn. Both Amos and LISREL can read in raw data from a variety of different programs, and both allow the user to estimate models by simply drawing a path diagram. However, Amos cannot accurately estimate models when the observed variables are categorical. PRELIS/LISREL and Mplus handle ordinal indicators by first estimating a polychoric correlation matrix and an asymptotic covariance matrix and employing these within a weighted least squares estimator. In LISREL the user must create these matrices first using PRELIS; in Mplus all the work is done by the program once indicators have been declared as categorical. All three software packages handle models assuming the latent variable to be continuous, although Mplus can also estimate models in which the latent variables are assumed to be categorical.

Consult the documentation for the respective package for additional information on Amos, LISREL, and Mplus. In addition, IU students, staff, and faculty may schedule an appointment with a consultant at the UITS Stat/Math Center by calling 5-4724 or emailing statmath@indiana.edu.

Amy Drayton, Takuya Noguchi, and Hun Myoung Park offered helpful suggestions to make this document more informative and readable, though they are not responsible for any errors that remain.

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