20231120 - update formative text

09-Structural-Equation-Modeling.Rmd

@@ -357,7 +357,9 @@ fitMeasures(formativeModel2Fit, "df")
 
 Thus, [formative constructs](#formativeConstruct) are challenging to use in a SEM framework.\index{construct!formative}\index{structural equation modeling!model identification}
 To estimate a [formative construct](#formativeConstruct) in a SEM framework, the [formative construct](#formativeConstruct) must be used in the context of a model that allows some constraints.\index{construct!formative}\index{structural equation modeling!model identification}\index{structural equation modeling!degrees of freedom}
-However, emerging techniques such as confirmatory composite analysis allow estimation of [formative](#formativeConstruct) latent factors [@Schuberth2023; @Yu2023].\index{construct!formative}\index{confirmatory composite analysis}
+A [formative](#formativeConstruct) latent factor includes a disturbance term, and is thus not entirely determined by the causal indicators [@Bollen2011].\index{construct!formative}
+A composite (such as in [principal component analysis](#pca)), by contrast, has no disturbance term and is therefore completely determined by the composite indicators [@Bollen2011].\index{construct!formative}
+Emerging techniques such as confirmatory composite analysis allow estimation of [formative](#formativeConstruct) composites [@Schuberth2023; @Yu2023].\index{construct!formative}\index{confirmatory composite analysis}
 
 ## Additional Types of SEM {#additionalSEMmodels}