In a pioneering research article, Wollack and colleagues suggested the "erasure detection index" (EDI) to detect test tampering. The EDI can be used with or without a continuity correction and is assumed to follow the standard normal distribution under the null hypothesis of no test tampering. When used without a continuity correction,…

The general use of the Spearman-Brown formula for calculating the reliability of parallel tests with different lengths is reviewed. The importance of the assumption that the component tests be parallel is noted and the property that parallel tests must be non-negatively correlated is derived. (Author)

Some problems associated with the criteria of reproducibility and scalability as they are used in Guttman scalogram analysis to evaluate cumulative, nonparametric scales of dichotomous items are discussed. A computer program is presented which analyzes response patterns elicited by dichotomous scales designed to be cumulative. (Author/DWH)

The tendency to extreme scores (TES) can affect sensitive indices, such as Cattell's coefficient of pattern similarity, so that a flat profile will, in general, be found more similar to a standard than will an extreme profile. TES is especially critical when profile matching is used in clinical diagnosis. (Author/BW)

The use of Bayes' estimates for proportions in the Law of Comparative Judgment is suggested to avoid sample proportions of zero and one. (Author)

Samples in research on individual and group differences may be selected based on whole scores which differ from the population mean. Children are diagnosed in clinical practice with a whole score. These procedures produce regression to the population mean which can affect accuracy and adequacy of part score interpretations. (Author/DWH)

A derivation of a formula for the stability coefficient is presented and discussed in terms of test reliability over time. (PR)

Alternate versions of Hutchinson's theory were compared, and one which implies the existence of partial knowledge was found to be better than one which implies that an appropriate measure of ability is obtained by applying the conventional correction for guessing. (Author/PN)