This article discusses the theoretical and practical contributions of Zumbo, Gadermann, and Zeisser's family of ordinal reliability statistics. Implications, interpretation, recommendations, and practical applications regarding their ordinal measures, particularly ordinal alpha, are discussed. General misconceptions relating to this family of…

Chalmers recently published a critique of the use of ordinal a[alpha] proposed in Zumbo et al. as a measure of test reliability in certain research settings. In this response, we take up the task of refuting Chalmers' critique. We identify three broad misconceptions that characterize Chalmers' criticisms: (1) confusing assumptions with…

Cultural consensus theory (CCT) is a data aggregation technique with many applications in the social and behavioral sciences. We describe the intuition and theory behind a set of CCT models for continuous type data using maximum likelihood inference methodology. We describe how bias parameters can be incorporated into these models. We introduce…

The graded response (GR) and generalized partial credit (GPC) models do not imply that examinees ordered by raw observed score will necessarily be ordered on the expected value of the latent trait (OEL). Factors were manipulated to assess whether increased violations of OEL also produced increased Type I error rates in differential item…

Two new prophecy formulas for estimating item response theory (IRT)-based reliability of a shortened or lengthened test are proposed. Some of the relationships between the two formulas, one of which is identical to the well-known Spearman-Brown prophecy formula, are examined and illustrated. The major assumptions underlying these formulas are…

Fifteen FORTRAN 77 programs are contained in the described package. Three programs are available for each of five forgetting models involving 5, 7, 8, 9, and 10-parameter models. The programs compute parameter estimates and test parameter estimates both between and within experimental conditions. (Author/GDC)

DICOT, a computer program for the Rasch analysis of classroom tests, is described. Results are presented in a self-explanatory form. Person ability and item difficulty estimates are expressed in a familiar metric. Person and item fit statistics provide a diagnosis of individual children and identification of problematic items. (Author/DWH)