library(lavaan)

## This is lavaan 0.6-8
## lavaan is FREE software! Please report any bugs.

## The industrialization and Political Democracy Example
## Bollen (1989), page 332
model <- '
  # latent variable definitions
     dem60 =~ y1 + y2 + y3 + y4
     dem65 =~ y5 + y6 + y7 + y8
     common =~ y1 + y2 + y3 + y4 + y5 + y6 + y7 + y8
     
  # latent correlations
  common ~~ 0*dem60 + 0*dem65
  dem65 ~ dem60
'

fit <- sem(model, data = PoliticalDemocracy)

## Warning in lavaan::lavaan(model = model, data = PoliticalDemocracy, model.type = "sem", : lavaan WARNING:
##     the optimizer warns that a solution has NOT been found!

fit2 <- sem(model, data = PoliticalDemocracy, meanstructure = TRUE)

sessionInfo()

## R version 4.0.5 (2021-03-31)
## Platform: x86_64-apple-darwin17.0 (64-bit)
## Running under: macOS Catalina 10.15.7
## 
## Matrix products: default
## BLAS:   /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRblas.dylib
## LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib
## 
## locale:
## [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
## 
## attached base packages:
## [1] stats     graphics  grDevices utils     datasets  methods   base     
## 
## other attached packages:
## [1] lavaan_0.6-8
## 
## loaded via a namespace (and not attached):
##  [1] digest_0.6.27     R6_2.5.0          jsonlite_1.7.2    stats4_4.0.5     
##  [5] magrittr_2.0.1    evaluate_0.14     rlang_0.4.10      stringi_1.5.3    
##  [9] jquerylib_0.1.3   bslib_0.2.4       pbivnorm_0.6.0    rmarkdown_2.11   
## [13] tools_4.0.5       stringr_1.4.0     xfun_0.22         yaml_2.2.1       
## [17] compiler_4.0.5    mnormt_2.0.2      tmvnsim_1.0-2     htmltools_0.5.1.1
## [21] knitr_1.36        sass_0.3.1