This article outlines a readily applicable procedure for point and interval estimation of the population discrepancy between reliability and the popular Cronbach's coefficient alpha for unidimensional multi-component measuring instruments with uncorrelated errors, which are widely used in behavioral and social research. The method is developed…

The aim of this study is to compare the results of correlation coefficient estimation of reliability with those obtained through the Bland-Altman plot technique. The scale was first divided into two halves using three different approaches. A linear and high-level relationship was found between the scale scores obtained from the halved forms.…

Careful considerations are necessary when there is a need to choose an anchor test form from a list of old test forms for equating under the random groups design. The choice of the anchor form potentially affects the accuracy of equated scores on new test forms. Few guidelines, however, can be found in the literature on choosing the anchor form.…

Classical approach to test theory has been the foundation for educational and psychological measurement for over 90 years. This approach concerns with measurement error and hence test reliability, which in part relies on individual test items. The CTT package, developed in light of this, provides functions for test- and item-level analyses of…