Before revision: Its functions support: Scale construction using factor analysis, cluster analysis, and reliability analysis Basic descriptive statistics Item response theory via factor analysis of tetrachoric and polychoric correlations Simulating item and test structures Structural equation modeling Psych creates graphical displays of path diagrams, factor analysis, and structural equation models using basic graphics.
After revision: Its functions support: Scale construction using factor analysis, cluster analysis, and reliability analysis Basic descriptive statistics Item response theory via factor analysis of tetrachoric and polychoric correlations Simulating item and test structures Structural equation modelling Psych creates graphical displays of path diagrams, factor analysis, and structural equation models using basic graphics.