Spearman's factor-analytic model has been proposed as a unidimensional linear item response theory (IRT) model for continuous item responses. This article first proposes a reexpression of the model that leads to a form similar to that of standard IRT models for binary responses and discusses the item indices of difficulty discrimination and…

The purpose of this study is to examine the effects of a false assumption regarding the motivation of examinees on test construction. Simulated data were generated using two models of item responses (the three-parameter logistic item response model alone and in combination with Wise's examinee persistence model) and were calibrated using a…

Examined the performance of DIMTEST, through simulation, for unidimensional and two-dimensional data that exhibited ceiling effects generated through changes in location and scale of the theta distribution. Results indicate that the power of DIMTEST is reduced as the location shifts upward and the scale shifts downward. Considers the selection…

Compared three methods for developing a common metric under item response theory through simulation. For smaller numbers of common items, linking using the characteristic curve method yielded smaller root mean square differences for both item discrimination and difficulty parameters. For larger numbers of common items, the three methods were…

A statistic used by R. Meijer (1994) to determine person-fit referred to the number of errors from the deterministic Guttman model (L. Guttman, 1950), but this was, in fact, based on the number of errors from the deterministic Guttman model as defined by J. Loevinger (1947, 1948). (SLD)

Computerized adaptive tests (CATs) are individualized tests that, from a measurement point of view, are optimal for each individual, possibly under some practical conditions. In the present study, it is shown that maximum information item selection in CATs using an item bank that is calibrated with the one- or the two-parameter logistic model…

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)

The concept of item discrimination is generalized to the case in which more than one ability is required to determine the correct response to an item, using the conceptual framework of item response theory and the definition of multidimensional item difficulty previously developed by M. Reckase (1985). (SLD)

In applying I. I. Bejar's method for detecting the dimensionality of achievement tests, researchers should be cautious in interpreting the slope of the principal axis. Other information from the data is needed in conjunction with Bejar's method of addressing item dimensionality. (SLD)

The power of the nonparametric person-fit statistic, U3, is investigated through simulations as a function of item characteristics, test characteristics, person characteristics, and the group to which examinees belong. Results suggest conditions under which relatively short tests can be used for person-fit analysis. (SLD)

Multidimensional item response theory (IRT) models have been proposed for better understanding the dimensional structure of data or to define diagnostic profiles of student learning. A compensatory multidimensional two-parameter partial credit model (M-2PPC) for constructed-response items is presented that is a generalization of those proposed to…

An approach to test modeling is illustrated that encompasses both response consistency and response difficulty. This generative approach makes validation an ongoing process. An analysis of hidden figure items with 60 high school students supports the feasibility of the method. (SLD)