We have the potential to substantially advance the field of health status assessment by constructing and calibrating questionnaires based on item response theory (IRT) and administering them using computerized adaptive methods. This opportunity could hardly come at a better time. The health care industry needs more practical tools to monitor population health on a large scale as well as more pr...

Ratings on performance tasks from two scoring sessions of an eighth grade mathematics examination, developed by the California State Department of Education, were used (a) to study the feasibility of estimating IRT rater severity information within a scoring session, (b) to investigate the variation in rater severity within rating sessions (which we called rater drift), and (c) to examine the r...

Since the Handbook of Human Intelligence appeared in 1982, the "psychometric approach" has changed dramatically. Traditionally, the psychometric approach was synonymous with the factor-analytic approach. Exploratory factor analysis was applied to discover the number and nature of the factors that underlie performance on cognitive tasks. Carroll's (1993) three-stratum model of intellect synthesi...

In a test, the testing score would be closer to examinee’s actual ability when careless mistakes were corrected. In CAT, however, changing the answer of one item in CAT might cause the following items no longer appropriate for estimating the examinee’s ability. These inappropriate items in a reviewable CAT might in turn introduce bias in ability estimation and decrease precision. An early propo...

This work presents a model for student knowledge diagnosis that can be used in ITSs for student model update. The diagnosis is accomplished through Computerized Adaptive Testing (CAT). CATs are assessment tools with theoretical background. They use an underlying psychometric theory, the Item Response Theory (IRT), for question selection, student knowledge estimation and test finalization. In pr...

A mantra often repeated in the introductory material to psychometrics and Item Response Theory (IRT) is that a Rasch model probabilistic version of Guttman scale. The idea comes from observation sigmoidal item response function provides characteristic models an It appears, however, more difficult reconcile assumption local independence, which traditionally accompanies model, with dependence exi...

We have analysed several multiwavelength optical observations (Hα, Hβ, Hǫ, Ca ii H & K, Ca ii IRT lines) of chromospherically active binary system OU Gem, taken in three observation runs: March 1996, April 1998 (using the SOFIN spectrograph and the Nordic Optical Telescope) and January 1999 (using the ESA-MUSICOS spectrograph and the Isaac Newton Telescope). The spectra show double Hα and Hβ ab...

Item Response Theory (IRT) models enable researchers to evaluate test or survey subjects and questions simultaneously to more accurately judge the difficulty and quality of the test as well as the strength of each subject. Most IRT analyses use parametric models, often without satisfying the necessary assumptions of these models. The KernSmoothIRT package uses kernel smoothing from Ramsay (1991...

In this paper the IRT project (Internet / Information Retrieval Tools) is described. The basic goal of IRT is to advise users of Internet search engines in retrieving information from the free public access part of the Internet. In achieving this, IRT has developed a model to evaluate search engines. This model is described in here. Evaluation criteria refer to functionality: search options, pr...