ABSTRACT
The most popular unidimensional method of attitude measurement involves ordered categories. More traditional names such as Summated Ratings, Likert Scaling and Semantic Differential are forms of ordered categories. The scaling method of successive intervals is an attempt to accommodate more items than other unidimensional techniques can and to estimate the distance or interval between the ordered categories. The Program TSCALE formulated by Veldman performs Successive Interval Scaling and is provided on the CD-ROM. Veldman's program differs slightly from Green's method but the relative positions of the objects remain much the same. The FORTRAN program for TSCALE can be found in Scaling Methods. Successive Interval Scaling and Likert Scaling, when carefully applied, often yield similar results. Cronbach's alpha is most commonly used to determine the reliability of a set of categorical ratings. Alpha reliability is based on the assumptions that item variance is error variance.
