Optimalisering van die omskakeling van matrieksimbole vir universiteitstoelatingsvereistes

Optimalisation of the conversion of matriculation symbols for university admission purposes The results demonstrate the potential benefits of taking symbols in individual matriculation subjects into account when predicting university performance. After the internal consistency of the matriculation symbol point totals (MSTs) of three different intakes of first-year students was improved by means of the Elliott-Strenta procedure, this explained a greater percentage (increases of between 0.91% and 3.33%) of the variance of the mean first-year university percentage mark (MPM). For a group of students with the same five matriculation subjects, the incremental gain in criterion variance explained varied between 7.46% and 9.84% when the regression coefficients obtained in a multiple regression were used. Moreover, if the coefficients obtained in this manner were used to weight the matriculation symbol points of subsequent years, the MST-MPM correlations rose similarly. For black students, increases of between 0.94% and 8.48% in explained criterion variance were obtained when the number of standard and lower grade subjects and the number of subjects taken from subject groups D, E and F were also included in a multiple regression equation. The implications of these findings for admissions research, following the introduction of the proposed Further Education and Training Certificate, are pointed out. (South African Journal of Education: 2003 23 (1): 45-51

Coefficient alpha : unnecessarily ambiguous ; unduly ubiquitous

By means of simple numerical examples it is demonstrated how the value of coefficient alpha is determined by the size and sign of the item intercorrelations, the dimensionality of the items, and the number of items. Relatively high alphas may be obtained for multidimensional item data (as obtained under a violation of essential tau-equivalence). Dimensionality analyses should therefore precede internal-consistency analyses if unidimensional tests are required. Such analyses also may alert one to the possibility of negative alpha values. Alternative coefficients are mentioned for situations when essential tau-equivalence is in doubt

Recent proposals to estimate transient error within the classical test theory tradition

Reliability is conceptually defined in terms of consistency across test occasions but coefficient alpha, the most popular reliability estimation method, precludes the examination of such consistency. Three recent proposals to estimate transient error separately within a classical test theory tradition, and the results that they have yielded are reviewed. The merits of these proposals are compared with those of generalisability theory which differentiates between different sources of error variation. Although the procedures reviewed cannot match the advantages of generalisability theory, they may be sufficient in many applications