What is "NA * variable" in lavaan package in R? (factor analysis)

user_11159724 0
Viewed 25
library(lavaan)

#model

fig2.5.data <- '
1
.5 1
.1 .1 1
.2 .3 .2 1
'

fig2.5.cor <- getCov(fig2.5.data, names=c(c("X1", "X2", "X3", "X4")))

fig2.5.model <- '
# latent variables
F1 =~ NA*X1 + a*X1 + b*X2
F2 =~ NA*X3 + c*X3 + d*X4

# variances/covariances

# fix variance to 1
F1 ~~ 1*F1

# fix variance to 1
F2 ~~ 1*F2
F1 ~~ e*F2

# label residual variances
X1 ~~ w*X1
X2 ~~ x*X2
X3 ~~ y*X3
X4 ~~ z*X4

It's an extract from the textbook I'm reading at the moment.

I understand everything else but "NA*" parts.

What are they?

I've encountered many NAs when using R, such as when there are missing data, but this one seems to be totally incomprehensible to me.

Any help would be much appreciated!

r-lavaan r
1 Answers

From lavaan's tutorial, page 12:

To force this factor loading to be free, we pre-multiply it with NA, as a hint to lavaan that the value of this parameter is ‘missing’ and therefore still unknown.

user_58519050
Related