Add Paths to Improve Fit
The three-factor model of the WAIS-III showed poor fit when examining the fit indices. You can use the modification indices to view potential parameter estimates to add to the model to improve fit. Correlated error terms are normal estimates to add, as the variance of the manifest variables on the same factor can be related to each other.
The data has been loaded for you and is called IQdata
. You can view the data using head(IQdata)
.
This exercise is part of the course
Structural Equation Modeling with lavaan in R
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Examine modification indices
modificationindices(wais.fit, sort = TRUE)
# Update the three-factor model
wais.model2 <- 'verbalcomp =~ vocab + simil + inform + compreh
workingmemory =~ arith + digspan + lnseq
perceptorg =~ piccomp + block + matrixreason + digsym + symbolsearch
___'