A general purpose toolbox for personality, psychometric theory and
experimental psychology. Functions are primarily for multivariate
analysis and scale construction using factor analysis, principal
component analysis, cluster analysis and reliability analysis,
although others provide basic descriptive statistics. Item Response
Theory is done using factor analysis of tetrachoric and polychoric
correlations. Functions for analyzing data at multiple levels include
within and between group statistics, including correlations and factor
analysis. Functions for simulating and testing particular item and
test structures are included. Several functions serve as a useful
front end for structural equation modeling. Graphical displays of
path diagrams, factor analysis and structural equation models are
created using basic graphics. Some of the functions are written to
support a book on psychometric theory as well as publications in
personality research. For more information, see the
personality-project.org/r web page.