Item response theory (IRT) has become one of the most popular scoring frameworks for measurement data. IRT models are used frequently in computerized adaptive testing, cognitively diagnostic assessment, and test equating. This article reviews two of the most popular software packages for IRT model estimation, BILOG-MG (Zimowski, Muraki, Mislevy, & Bock, 1996) and MULTILOG (Thissen, 1991), which...

Circulating immunoreactive trypsinogen (IRT), a biomarker of exocrine pancreatic disease in cystic fibrosis (CF), is elevated in most CF newborns. In those with severe CF transmembrane conductance regulator (CFTR) genotypes, IRT declines rapidly in the first years of life, reflecting progressive pancreatic damage. Consistent with this progression, a less elevated newborn IRT measure would refle...

The isovolumetric relaxation time of the left ventricle (IRT) in 20 hypothyroid patients (133 +/- (SE of mean) 4 ms) was significantly longer than that in 23 normal subjects (95 +/- 3 ms). During a trial of thyroxine replacement the IRT in 12 hypothyroid patients fell from 143 +/- 4 ms to 107 +/- 4 ms. The IRT seems to be a useful index of end-organ function in hypothyroidism.

The research reactor IRT-2000 at the Institute for Nuclear Research and Nuclear Energy (INRNE) in Sofia was built and put into operation in 1961. It was temporarily shut down in 1989 for improvement. The reconstruction into IRT-200 is being carried out under the decision of the Council of Ministers of Republic of Bulgaria in 2001. The strategy for sustainable utilization considers the IRT-200 a...

There are two currently popular statistical frameworks for addressing measurement problems namely Classical Test Theory (CTT) and Item Response Theory (IRT). This study is aimed empirically to examine the similarities and differences in the parameters estimated using these two frameworks. For this purpose, firstly the model assumptions and the goodness of fit analyses were checked for IRT. The ...

The liver, pancreas, and heart are particularly susceptible to iron-related disorders. These tissues take up plasma iron from transferrin or non-transferrin-bound iron, which appears during iron overload. Here, we assessed the effect of iron status on the levels of the transmembrane transporters, ZRT/IRT-like protein 14 and divalent metal-ion transporter-1, which have both been implicated in tr...

The effectiveness of confirmatory factor analytic (CFA) and item response theory (IRT) methods of assessing measurement invariance were investigated using simulated data with a known lack of invariance. Across all study conditions, IRT likelihood ratio (LR) tests consistently outperformed both CFA and IRT differential functioning of items and tests (DFIT) analyses in terms of detecting a lack o...

INTRODUCTION The Health Assessment Questionnaire Disability Index (HAQ) and the SF-36 PF-10, among other instruments, yield sensitive and valid Disability (Physical Function) endpoints. Modern techniques, such as Item Response Theory (IRT), now enable development of more precise instruments using improved items. The NIH Patient Reported Outcomes Measurement Information System (PROMIS) is charge...

Illegal hunting (poaching) is a global threat to wildlife. Anti-poaching initiatives are making increasing use of technology, such as infrared thermography (IRT), to support traditional foot and vehicle patrols. To date, the effectiveness of IRT for poacher location has not been tested under field conditions, where thermal signatures are often complex. Here, we test the hypothesis that IRT will...