Background During the past few decades, there have been many studies conducted to evaluate the comparative performance of differential item functioning (DIF) methods under various conditions. These conditions, for example, include small and unbalanced sample size between groups (Woods 2009), short tests (Paek and Wilson 2011), various levels of DIF contamination (Finch 2005), multilevel data (F...

This study examines measurement invariance of student perceptions teaching quality collected in five countries: Indonesia (n students = 6,331), the Netherlands 6,738), South Africa 3,422), Korea 6,997) and Spain 4,676). The administered questionnaire was My Teacher Questionnaire (MTQ). Student perceived teachers’ estimated using partial credit model (PCM). Tests for differential item functionin...

As part of test score validity, differential item functioning (DIF) is a quantitative characteristic used to evaluate potential item bias. In applications where a small number of examinees take a test, statistical power of DIF detection methods may be affected. Researchers have proposed modifications to DIF detection methods to account for small focal group examinee sizes for the case when item...

Marker frequency analysis of the Escherichia coli recB mutant chromosome has revealed a deficit of DNA in a specific zone of the terminus, centred on the dif/TerC region. Using fluorescence microscopy of a marked chromosomal site, we show that the dif region is lost after replication completion, at the time of cell division, in one daughter cell only, and that the phenomenon is transmitted to p...

In Drosophila embryos, dorsal-ventral polarity is defined by a signal transduction pathway that regulates nuclear import of the Dorsal protein. Dorsal protein's ability to act as a transcriptional activator of some zygotic genes and a repressor of others defines structure along the dorsal-ventral axis. Dorsal is a member of a group of proteins, the Rel-homologous proteins, whose activity is reg...

One important role of DIF, the stalk cell-specific inducer of Dictyostelium, may be to divert cells from the spore cell pathway of differentiation. The D19 gene encodes an mRNA which is highly enriched in prespore over prestalk cells in the migratory slug. We show, using a mutant defective in DIF accumulation, that the concentration of D19, and several other prespore mRNA sequences, decreases i...

The psychometric properties of instruments used to measure self-reported experiences of discrimination in epidemiologic studies are rarely assessed, especially regarding construct validity. The authors used 2000-2001 data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study to examine differential item functioning (DIF) in 2 versions of the Experiences of Discrimination (EOD...

Background: To assess and correlate the clinical, histopathological and DIF features and compare the sensitivity of DIF with that of histopathology in autoimmune bullous disorders of skin. Methods: A cross-sectional descriptive hospital based study was conducted on 45 patients who had active vesicobullous lesions. After a detailed cutaneous examination, two punch biopsies were taken, one from l...

Prespore and prestalk cells can be distinguished within aggregates of Dictyostelium by the expression of well-characterized cell type-specific genes. Fusion of the tagB regulatory region to Escherichia coli beta-galactosidase revealed that this prestalk specific gene marks the differentiation of the initial prestalk cell population, PST-1. The reporter gene was expressed normally in tagB- mutan...