A subset S of vertices in a graph G is called a total irredundant set if, for each vertex v in G, v or one of its neighbors has no neighbor in S − {v}. The total irredundance number, ir(G), is the minimum cardinality of a maximal total irredundant set of G, while the upper total irredundance number, IR(G), is the maximum cardinality of a such set. In this paper we characterize all cubic graphs ...

This study aimed at examining the issues affecting the use of IRT models in investigating differential item functioning in high stakes testing. It specifically focused on the Iranian National University Entrance Exam (INUEE) Special English Subtest. A sample of 200,000 participants was randomly selected from the candidates taking part in the INUEE 2003 and 2004 respectively. The data collected ...

Mega- or meta-analytic studies (e.g. genome-wide association studies) are increasingly used in behavior genetics. An issue in such studies is that phenotypes are often measured by different instruments across study cohorts, requiring harmonization of measures so that more powerful fixed effect meta-analyses can be employed. Within the Genetics of Personality Consortium, we demonstrate for two c...

BACKGROUND Intracoronary radiation therapy (IRT) is the only proven treatment for in-stent restenosis (ISR). It is, however, associated with a significant failure rate. The present study evaluated the outcomes of patients who underwent repeat intracoronary radiation for recurrent ISR. METHODS AND RESULTS Fifty-one consecutive patients who failed a previous radiation treatment, presented with ...

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...