This paper describes procedures for estimating single-administration classification consistency and accuracy indices using item response theory (IRT). This IRT approach is applied to real test data comprised of mixtures of dichotomous and polytomous items. Several different IRT model mixtures are considered. Comparisons are made between the IRT approach and two non-IRT procedures.

OBJECTIVE Because cystic fibrosis can be difficult to diagnose and treat early, newborn screening programs have rapidly developed nationwide but methods vary widely. We therefore investigated the costs and consequences or specific outcomes of the 2 most commonly used methods. METHODS With available data on screening and follow-up, we used a simulation approach with decision trees to compare i...

the classical test theory (ctt) and item response theory (irt) are widely used in construction and analysis of exams and questionnaires. because of the various shortcomings of ctt, irt has been designed. even though irt has overcome most of the limitations of ctt and has made computer adaptive testing possible, it is still important to point out that not enough reasons exist to totally discard ...

AIMS To investigate the immunoreactive trypsinogen (IRT) values above the usual 99th centile laboratory cut-off and determine the value of offering further testing to those infants with a markedly elevated IRT but no cystic fibrosis transmembrane regulator (CFTR) gene mutation identified by the screening programme. METHODS All babies born in Victoria, Australia, between 1991 and 2003, were sc...

OBJECTIVE To compare three cystic fibrosis (CF) newborn screening strategies used in Victoria since 1989. DESIGN, SETTING AND PARTICIPANTS Retrospective review of newborn screening and clinical records for people with CF born in Victoria between 1989 and 2008 to compare screening strategies: repeat immunoreactive trypsinogen (IRT) testing (IRT/IRT, 1989-1990), IRT and p.F508del mutation analy...

Serum immunoreactive trypsin (IRT) concentrations were measured blind in sera from 33 patients with cystic fibrosis and in 32 age-matched controls. Thirty-two patients had abnormal trypsin concentrations. In 30 of these patients the level of IRT was very low whereas in the other two (the youngest of the group) it was extremely high. All 30 patients with low IRT concentrations had clinical or bi...

The inspiratory drive to hypoglossal (XII) motoneurons originates in the caudal medullary intermediate reticular (IRt) region. This drive is mainly glutamatergic, but little is known about the neurochemical features of IRt XII premotor neurons. Prompted by the evidence that XII motoneuronal activity is controlled by both muscarinic (M) and nicotinic cholinergic inputs and that the IRt region co...

BACKGROUND Since its beginnings, newborn screening for cystic fibrosis (CF) using an assay for immunoreactive trypsinogen (IRT) has been plagued by a high rate of false-positive results (screen positive, diagnosis negative), despite attempts to reduce this rate by use of altered cutoffs and second-tier DNA testing. IRT exists as 2 isoforms: IRT1 and IRT2, with IRT2 being more closely aligned wi...

CONTEXT Item response theory (IRT) measurement models are discussed in the context of their potential usefulness in various medical education settings such as assessment of achievement and evaluation of clinical performance. PURPOSE The purpose of this article is to compare and contrast IRT measurement with the more familiar classical measurement theory (CMT) and to explore the benefits of IR...