The information matrix for the parameters in a latent-variable model is bounded from above by the information that would obtain if the values of the latent variables could also be observed. The difference is the "missing information." This paper discusses the structure of the information matrix, and characterizes the degree to which…

The structure of information matrices in latent-variable models is explicated, and the degree to which missing information can be recovered by exploring collateral variables for respondents is characterized. Results are illustrated in the context of item-response-theory models, and practical implications are discussed. (SLD)

The view of learning that underlies standard test theory is inconsistent with the view rapidly emerging from cognitive and educational psychology. Learners become more competent not simply by learning more facts and skills, but by reconfiguring their knowledge; by "chunking" information to reduce memory loads; and by developing…

Advances in cognitive research increase the need for assessment that can address the processes and the strategies by which persons solve problems. Several psychometric models have been introduced to handle claims cast in information-processing terms, explicitly modeling performance in terms of theory-based predictions of performance. Cognitively…

It is a common practice in item response theory (IRT) to treat estimates of item parameters, say "B" circumflex, as if they were the known, true quantities, "B." However, ignoring the uncertainty associated with item parameters can lead to biases and over-confidence in subsequent inferences such as ability estimation,…

The models of standard test theory, having evolved under a trait-oriented psychology, do not reflect the knowledge structures and the problem-solving strategies now seen as central to understanding performance and learning. In some applications, however, key qualitative distinctions among persons as to structures and strategies can be expressed…

In educational assessment, what students say, do, and sometimes make is observed, and assessors attempt to infer what students know, can do, or have accomplished more generally. Some links in the chain of inference depend on statistical models and probability-based reasoning, and it is with these links that terms such as validity, reliability, and…

Psychologist Andrea diSessa coined the term "phenomenological primitives", or p-prims, to talk about nonexperts' reasoning about physical situations. P-prims are primitive in the sense that they stand without significant explanatory substructure or explanation. Examples are "Heavy objects fall faster than light objects" and "Continuing force is…

A framework is described for exploiting auxiliary information about test items within item response theory models to enhance parameter estimates. The method also provides diagnostic information about items' operating characteristics. An empirical Bayesian estimation of Rasch item difficulty is used to illustrate the principles involved. (TJH)

The theoretical approaches taken by the LOGIST and BILOG computer programs for estimating the parameters of the three-parameter logistic item response model, and their practical consequences, are compared. Guidelines for choosing between the programs for particular applications are offered. (SLD)

A situated/sociocultural (SC) view of assessment "emphasizes questions about the quality of students' participation in activities of inquiry and sense-making, and considers assessment practices as integral components of the general systems of activity in which they occur" (Greeno, Collins, & Resnick, 1997, p. 36). This presentation addresses two…

A model is presented for item responses when different examinees use different strategies to arrive at their answers and when only those answers, not choice or strategy or subtask results, can be observed. Using substantive theory to differentiate the likelihoods of response vectors under a fixed set of solution strategies, responses are modeled…

The most familiar models of item response theory are defined at the level of individual subjects. It is possible, however, to define such models for groups of subjects. This paper discusses group-level item response models, their uses, and their relationships to subject-level models. (Author/JKS)

This article addresses issues in model building and statistical inference in the context of student modeling. The use of probability-based reasoning to explicate hypothesized and empirical relationships and to structure inference in the context of proportional reasoning tasks is discussed. Ideas are illustrated with an example concerning…

Conventional methods of multivariate normal analysis do not apply when the variables of interest are not observed directly, but must be inferred from fallible or incomplete data. For example, responses to mental test items may depend upon latent aptitude variables, which modeled in turn as functions of demographic effects in the population. A…