(26 May 2014): the slides from the special session on the lavaan ecosystem during the Modern Modeling Methods Conference (May 20-21, University of Connecticut) are now available here.

(26 May 2014): Alex Beaujean has published a book on Latent Variable Modeling Using R: A Step by Step Guide focusing on the lavaan package.

(24 April 2014): the lavaan paper has been downloaded >20.000 times.

(7 March 2014): version 0.5-16 has been released on CRAN. See Version History for more information.

The lavaan package is developed to provide useRs, researchers and teachers a free open-source, but commercial-quality package for latent variable modeling. You can use lavaan to estimate a large variety of multivariate statistical models, including path analysis, confirmatory factor analysis, structural equation modeling and growth curve models.

The official reference to the lavaan package is the following paper:

Yves Rosseel (2012). lavaan: An R Package for Structural Equation Modeling.

Journal of Statistical Software, 48(2), 1-36. URL http://www.jstatsoft.org/v48/i02/

To get a first impression of how lavaan works in practice, consider the following example of a SEM model. The figure below contains a graphical representation of the model that we want to fit.

```
model <- '
# latent variables
ind60 =~ x1 + x2 + x3
dem60 =~ y1 + y2 + y3 + y4
dem65 =~ y5 + y6 + y7 + y8
# regressions
dem60 ~ ind60
dem65 ~ ind60 + dem60
# residual covariances
y1 ~~ y5
y2 ~~ y4 + y6
y3 ~~ y7
y4 ~~ y8
y6 ~~ y8
'
fit <- sem(model,
data=PoliticalDemocracy)
summary(fit)
```