The nonequivalent groups anchor test (NEAT) design is often used to scale item parameters from two different test forms. A subset of items, called the anchor items or common items, are administered as part of both test forms. These items are used to adjust the item calibrations for any differences in the ability distributions of the groups taking…

Cognitive diagnostic models (CDMs) attempt to uncover latent skills or attributes that examinees must possess in order to answer test items correctly. The DINA (deterministic input, noisy "and") model is a popular CDM that has been widely used. It is shown here that a logistic version of the model can easily be fit with standard software for…

In this study, all the advantages of slope parameters, random weights, and latent regression are acknowledged when dealing with component and composite items by adding slope parameters and random weights into the standard item response model with internal restrictions on item difficulty and formulating this new model within a multilevel framework…

The accuracy of item parameter estimates in the multidimensional item response theory (MIRT) model context is one that has not been researched in great detail. This study examines the ability of two confirmatory factor analysis models specifically for dichotomous data to properly estimate item parameters using common formulae for converting factor…

Common items with inconsistent b-parameter estimates may have a serious impact on item response theory (IRT)--based equating results. To find a better way to deal with the outlier common items with inconsistent b-parameters, the current study investigated the comparability of 10 variations of four IRT-based equating methods (i.e., concurrent…

Winsteps (Rasch Measurement Software and Publications, 2003), as its name implies, is a psychometric program created specifically to compute the step function (Wright & Masters, 1982) for exams carrying partial-credit items. Despite the clarity of the Rasch model (Bond & Fox, 2001) and the availability of rich features in the program, such as the…

For measurement of multiple traits, this paper proposes assembling tests based on the targets for the variance functions of the estimators of each of the traits. A linear programming model is presented to computerize the assembly process. An example of test assembly from a two-dimensional item pool is provided. (SLD)

The capability of the DIMTEST statistical test in assessing essential unidimensionality of item responses to real tests was investigated for 22 real tests of at least 25 items and 700 or more examinees. DIMTEST results on real tests were able to discriminate between essentially unidimensional and multidimensional tests. (SLD)

Studied the effects of test dimensionality, theta distribution shape, and estimation program (BILOG, MULTILOG, or XCALIBRE) on the accuracy of item and person parameter estimates through simulation. Derived guidelines for estimating parameters of multidimensional test items using unidimensional item response theory models. (SLD)

The characteristics of unidimensional ability estimates obtained from data generated using multidimensional compensatory models were compared with estimates from non-compensatory item response theory (IRT) models. The least squares matching procedures used represent a good method of matching the two multidimensional IRT models. (TJH)

A well-known problem in the analysis of test and questionnaire data is that some item scores may be missing. Advanced methods for the imputation of missing data are available, such as multiple imputation under the multivariate normal model and imputation under the saturated logistic model (Schafer, 1997). Accompanying software was made available…

To determine which produced the most accurate item parameter estimates, four methods of item response theory were evaluated: (1) heuristic estimates; (2) the ANCILLES program; (3) the LOGIST program; and (4) the ASCAL program. LOGIST and ASCAL produced estimates of superior and essentially equivalent accuracy. (SLD)