Validation of the Persian Translation of the Children's Test Anxiety Scale: A Multidimensional Rasch Model Analysis.

In this study, we examine the psychometric properties of the Persian translation of the Children's Test Anxiety Scale (CTAS) using the Rasch rating scale model. In the first step, rating scale diagnostics revealed that the thresholds were disordered. To remedy this problem, two categories were collapsed and a rating scale structure with three points turned out to have optimal properties. Principal component analysis (PCA) of standardized residuals showed that the scale is not unidimensional. Since the scale is designed to measure three distinct dimensions of test anxiety we fitted a correlated three-dimensional Rasch model. A likelihood ratio test showed that the three-dimensional model fits significantly better than a unidimensional model. Principal component analysis of standardized residuals indicated that three subscales are unidimensional. Infit and outfit statistics indicated that one item misfitted the model in all the analyses. Medium correlations between the dimensions was evidence of the distinctness of the subscales and justifiability of the multidimensional structure for the scale. Criterion-related evidence was provided by correlating the scale with the Spence Children's Anxiety Scale (SCAS). The patterns of correlations provided evidence of convergent-discriminant validity. Findings suggest that a three-dimensional instrument with a 3-point Likert scale works best in the Persian language.