Structural Equation Models (sem)

sem is an R package for fitting structural-equation models. The package supports general structural equation models with latent varibles, fit by maximum likelihood assuming multinormality and generalized least squares, and single-equation estimation for observed-variable models by two-stage least.squares. There is support for computing robust standard errors and tests, and for multi-group models.

The sem package is available on the Comprehensive R Achive Network (CRAN).

For more information (now quite out of date), see J. Fox (2006), "Structural Equation Modeling With the sem Package in R." Structural Equation Modeling, 13:465-486, and the package help pages, which include many examples.

The current version of the sem package was written by John Fox, Zhenghua Nie, and Jarrett Byrnes.

Please address comments, questions, and suggestions to  jfox AT

Last Modified: 8 September 2012 by John Fox, jfox AT