This package contains an implementation of a the bootstrap test for underlying non-normality proposed by Foldnes and Gronneberg (Structural Equation Modeling, 2019). Also contains an adjusted polychoric estimator proposed by Gronneberg and Foldnes (Psychological Methods, 2022).
You can install:
-
the stable release on CRAN:
install.packages("discnorm") -
the latest development version:
devtools::install_github("njaalf/discnorm")
The package offers function bootTest() which tests an ordinal data frame for underlying normality. A function catLSadj() is provided that computes the adjusted polychoric correlations based on user-provided non-normal marginals.
Njål Foldnes & Steffen Grønneberg (2019) Pernicious Polychorics: The Impact and Detection of Underlying Non-normality, Structural Equation Modeling: A Multidisciplinary Journal, DOI: 10.1080/10705511.2019.1673168
Steffen Grønneberg & Njål Foldnes (2022) Factor Analyzing Ordinal Items Requires Substantive Knowledge of Response Marginals, Psychological Methods, DOI: 10.1037/met0000495