Psychometric Toolbox  
Reliability Analisys  

Description Function Item Factor Analysis > FABased Item Analysis and omega reliability estimation. The IFA function (a) assesses the dimensionality of a set of items according to the linear factor analysis (FA) model, (b) performs item and scale analysis on the basis of the unidimensional FA submodel, and (c) estimates the reliability of the test scores with the omega coefficient. The function contains two computing subfunctions: (a) Item appropriateness, which assess the appropriateness of the data and the unidimensionality assumption, and (b) item factor analysis, which performs unidimensional FAbased item analysis for the set of items. The results displayed in the itemanalysis output are the item means (difficulty indices), the standardized factor loadings (item discriminations) and the squared factor loadings (item reliabilities). Finally, IFA provides the omega reliability estimate for the test scores together with its 90% confidence interval. The only information it needs are the items that will be used for the analysis. Download example data file: Item_factor_analysis.zip 

