blavaan is a free, open source R package for Bayesian latent variable analysis. It relies on JAGS and Stan to estimate models via MCMC.

The blavaan functions and syntax are similar to lavaan. For example, consider the Political Democracy example from Bollen (1989):

```
library(lavaan) # for the PoliticalDemocracy data
library(blavaan)
model <- '
# latent variable definitions
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 <- bsem(model, data = PoliticalDemocracy)
summary(fit)
```

The development version of blavaan (containing updates not yet on CRAN) can be installed via the command below. Compilation is required; this may be a problem for users who currently rely on a binary version of blavaan from CRAN.

For further information, see:

Merkle, E. C., Fitzsimmons, E., Uanhoro, J., & Goodrich, B. (2021). Efficient Bayesian structural equation modeling in Stan. Journal of Statistical Software, 100(6), 1–22.

Merkle, E. C., & Rosseel, Y. (2018). blavaan: Bayesian structural equation models via parameter expansion. Journal of Statistical Software, 85(4), 1–30.

blavaan is supported by the Institute of Education Sciences, U.S. Department of Education, Grant R305D210044, as well as NSF grants SES-1061334 and 1460719.