The central idea in building and maintaining an item bank is to calibrate all the items onto a "common variable." The arithmetic involved in the calibration process is presented. It is recommended that an analysis of fit be done in every application to verify that the estimates of item difficulties are in fact sample-free. These…

Three equating methods were compared in terms of magnitude of scale drift: equipercentile equating, linear equating, and item response theory (IRT) equating. A sample of approximately 2670 cases was selected for each pairing of a form of the Scholastic Aptitude Tests (SAT) and an anchor test. Of the two conventional equating methods,…

Issues concerning equating test scores are discussed in an introduction, four papers, and two commentaries. Equating methods research, sampling errors, linear equating, population differences, sources of equating errors, and a circular equating paradigm are considered. (SLD)

The analytical decomposition demonstrates how the effects of item characteristics, test properties, individual examinee responses, and rounding rules combine to produce the item deletion effect on the equating/scaling function and candidate scores. The empirical portion of the report illustrates the effects of item deletion on reported score…

Estimation techniques for generating the covariance matrix for two new tests and an existing test without the necessity of any examinee having to take two complete tests is presented. An application of these techniques to linear, observed-score, test equating is presented. (Author/JKS)

Proper maintenance of a scale established in the baseline year would assure the accurate estimation of growth in subsequent years. Scale maintenance is especially important when the state performance standards must be preserved for future administrations. To ensure proper maintenance of a scale, the selection of anchor items and evaluation of…

A set of linear conditions on the item response functions is derived that guarantees identical observed-score distributions on two test forms. The conditions can be added as constraints to a linear programming model for test assembly that assembles a new test form to have an observed-score distribution optimally equated to the distribution of the…

A competency test was developed to assess students skills in using electronic library resources. Because all students were required to pass the test, and had multiple opportunities to do so, multiple test forms were desired. Standards had been set on the original form, and minor differences in form difficulty needed to be taken into account.…

A constrained computerized adaptive testing (CAT) algorithm is presented that automatically equates the number-correct scores on adaptive tests. The algorithm can be used to equate number-correct scores across different administrations of the same adaptive test as well as to an external reference test. The constraints are derived from a set of…

The stability of a physical disability construct was examined across instruments and samples, not to report a formal equating of instrument calibrations, but to indicate whether such an effort could succeed. Implications of using Rasch analysis, often used in educational research, and the possibility of developing a universal metric are discussed.…

Five forms of a basic science examination administered over three years in a national board testing program were analyzed to determine the stability of judged cut scores. Results indicate that cut scores derived from the modified Nedelsky procedure were within equating error of the Rasch equated cut scores over the five administrations. (SLD)

Potential benefits of using item response theory in test construction are evaluated using the experience and evidence accumulated during nine years of using a three-parameter model in the development of major achievement batteries. Topics addressed include error of measurement, test equating, item bias, and item difficulty. (TJH)

The equating methods and sampling designs used in the empirical studies in this special issue on the use of matched samples for test equating are described. Four requisites for equating are listed, and the invariance of equating functions requisite is identified as the focus of this issue. (SLD)

A method is proposed for equating different sets of items administered to different groups using the Rasch model. The Rasch equating model formulated describes one common Rasch scale in different groups with different but overlapping item sets. The model, based on the quasi-loglinear Rasch model, can be tested globally. (SLD)

An asymptotic expression for the reliability of a linearly equated test is developed using normal theory. Reliability is expressed as the product of test reliability before equating and an adjustment term that is a function of the sample sizes used to estimate the linear equating transformation. The approach is illustrated. (SLD)