Model the WAIS-III IQ Scale

Structural Equation Modeling with lavaan in R

Erin Buchanan

Professor

WAIS-III Model

• The WAIS-III has four latent variables measured by 12 manifest variables.
• The model also includes a second layer of latent variables:
  • Verbal IQ predicts verbal comprehension and working memory.
  • Perceptual IQ predicts perceptual organization and processing speed.
• These factors are likely highly correlated.

How to Get Started

• Build the first level of latents.
  • Make sure the four factors of the WAIS-III run properly.
  • Check for Heywood cases and bad fit.
• Add the second level of latents.

Let's practice!

Structural Equation Modeling with lavaan in R