This study was conducted in order to evaluate available linking techniques for forming large item pools and to make recommendations as to which techniques should be used under various circumstances. Variables of interest included calibration model and procedure, sample size, overlap level, and linking procedure. The calibration models considered…

A new indicator of item difficulty, which identifies effectiveness ranges, overcomes the limitations of other item difficulty indexes in describing the difficulty of an item or a test as a whole and in aiding the selection of appropriate ability level items for a test. There are three common uses of the term "item difficulty": (1) the probability…

The purpose of this paper is to present a generalization of the concept of item difficulty to test items that measure more than one dimension. Three common definitions of item difficulty were considered: the proportion of correct responses for a group of individuals; the probability of a correct response to an item for a specific person; and the…

The usefulness of a latent trait model designed for use with multidimensional test data was investigated in two stages. The first stage consisted of generating simulation data to fit the multidimensional extension of the two-parameter logistic model, applying the model to the data, and comparing the resulting estimates with the known parameters.…

A class of multidimensional latent trait models is described. The properties of the model parameters, and initial results on the accuracy of a maximum likelihood procedure for estimating the model parameters are discussed. The model presented is a special case of the general model described by Rasch (1961), with close similarities to the models…

Confirmatory multidimensional item response theory (CMIRT) was used to assess the structure of the Graduate Record Examination General Test, about which much information about factorial structure exists, using a sample of 1,001 psychology majors taking the test in 1984 or 1985. Results supported previous findings that, for this population, there…

Several special cases of the general Rasch model, varying in complexity, were investigated to determine whether they could successfully model realistic multidimensional item response data. Whether the parameters of the model could be readily interpreted was also investigated. The models investigated included: (1) the vector model; (2) the product…

To assess the effects of correlated abilities on test characteristics, and to explore the effects of correlated abilities on the use of a multidimensional item response theory model which does not explicitly account for such a correlation, two tests were constructed. One had two relatively unidimensional subsets of items, the other had all…

Six procedures for combining sets of item response theory (IRT) item parameter estimates from different samples were evaluated using real and simulated response data. Results support use of covariance matrix-weighted averaging and a procedure using sample-size-weighted averaging of estimated item characteristic curves at the center of the ability…