We compared coefficient alpha with five alternatives (omega total, omega RT, omega h, GLB, and coefficient H) in two simulation studies. Results showed for unidimensional scales, (a) all indices except omega h performed similarly well for most conditions; (b) alpha is still good; (c) GLB and coefficient H overestimated reliability with small…

Broadly conceived, reliability involves quantifying the consistencies and inconsistencies in observed scores. Generalizability theory, or G theory, is particularly well suited to addressing such matters in that it enables an investigator to quantify and distinguish the sources of inconsistencies in observed scores that arise, or could arise, over…

Test homogeneity and internal consistency reliability indices were developed on the basis of theoretical considerations of properties of hierarchical structures of data matrices. This reconceptualization, in terms of ordinal test theory, has potential for explication of the mutual relationship of test reliability and homogeneity. (TJH)