Crossing, or intersecting, differential item functioning (DIF) is a form of nonuniform DIF that exists when the sign of the between-group difference in expected item performance changes across the latent trait continuum. The presence of crossing DIF presents a problem for many statistics developed for evaluating DIF because positive and negative…

The majority of large-scale assessments develop various score scales that are either linear or nonlinear transformations of raw scores for better interpretations and uses of assessment results. The current formula for coefficient alpha (a; the commonly used reliability coefficient) only provides internal consistency reliability estimates of raw…

Models of modern test theory imply statistical independence among responses, generally referred to as "local independence." One violation of local independence occurs when the response to one item governs the response to a subsequent item. Expanding on a formulation of this kind of violation as a process in the dichotomous Rasch model,…

An adaptive testing method is presented that controls the speededness of a test using predictions of the test takers' response times on the candidate items in the pool. Two different types of predictions are investigated: posterior predictions given the actual response times on the items already administered and posterior predictions that use the…

In this article, a distinction is made between absolute and relative measurement. Absolute measurement refers to the measurement of traits on a group-invariant scale, and relative measurement refers to the within-group measurement of traits, where the scale of measurement is expressed in terms of the within-group position on a trait. Relative…

Examines the relationship between Cronbach's coefficient alpha and the reliability of a composite of a prespecified set of interrelated nonhomogeneous components through simulation. Shows that alpha can over- or underestimate scale reliability at the population level. Illustrates the bias in terms of structural parameters. (SLD)

Introduces a new Item Response Theory (IRT) based statistic for detecting answer copying. Compares this omega statistic with the best classical test theory-based statistic under various conditions, and finds omega superior based on Type I error rate and power. (SLD)

Examined the influence of deviant scale items on item parameter estimates of focal scale items and person parameter estimates through a comparison of item response theory (IRT) and classical test theory (CTT) models. Used Monte Carlo methods to explore results from a pilot investigation of job attitude data. Discusses implications for researchers…

Traditionally, error in equating observed scores on two versions of a test is defined as the difference between the transformations that equate the quantiles of their distributions in the sample and population of test takers. But it is argued that if the goal of equating is to adjust the scores of test takers on one version of the test to make…

Polynomial algorithms are presented that are used to solve selected problems in test theory, and computational results from sample problems with several hundred decision variables are provided that demonstrate the benefits of these algorithms. The algorithms are based on optimization theory in networks (graphs). (SLD)

The usefulness of three item response theory-based methods and the Mantel Haenszel technique in evaluating the measurement equivalence of translated assessment instruments was demonstrated in a study involving 2,000 French-speaking Canadian adults who took a French test translation and 2,000 English-speaking adults who took the English original.…