BACKGROUND Rasch analysis with a focus on Differential Item Functioning (DIF) is increasingly used for examination of psychometric properties of health outcome measures. To take account of DIF in order to retain precision of measurement, split of DIF-items into separate sample specific items has become a frequently used technique. The purpose of the paper is to present and summarise recent adva...

Title of Dissertation: EXAMINING DIFFERENTIAL ITEM FUNCTIONING FROM A LATENT CLASS PERSPECTIVE Karen Samuelsen, Doctor of Philosophy, 2005 Dissertation directed by: C. Mitchell Dayton Department of Measurement, Statistics and Evaluation Current approaches for studying differential item functioning (DIF) using manifest groups are problematic since these groups are treated as homogeneous in natur...

Years of completed education is a powerful correlate of performance on mental status assessment. This analysis evaluates differences in cognitive performance attributable to level of education and sex. We analyzed Mini-Mental State Examination responses from a large community sample (Epidemiologic Catchment Area study, N = 8,556), using a structural equation analytic framework grounded in item ...

Background The purpose of this study was to evaluate the effectiveness of two methods of detecting differential item functioning (DIF) in the presence of multilevel data and polytomously scored items. The assessment of DIF with multilevel data (e.g., patients nested within hospitals, hospitals nested within districts) from large-scale assessment programs has received considerable attention but ...

Objective. The present study uses simulated data to find what the optimal number of response categories is to achieve adequate power in ordinal logistic regression (OLR) model for differential item functioning (DIF) analysis in psychometric research. Methods. A hypothetical ten-item quality of life scale with three, four, and five response categories was simulated. The power and type I error ra...

To date, many studies have been conducted to compare the performance of different DIF procedures using simulated data sets. However, some results from these simulation studies are inconsistent with one other (e.g., Hidalgo & López-Pina, 2004; Jodoin & Gierl, 2001). This study used real data to systematically investigate the consistencies of DIF detection and effect size among three widely-used ...

BACKGROUND For the Low Vision Quality Of Life questionnaire (LVQOL) it is unknown whether the psychometric properties are satisfactory when an item response theory (IRT) perspective is considered. This study evaluates some essential psychometric properties of the LVQOL questionnaire in an IRT model, and investigates differential item functioning (DIF). METHODS Cross-sectional data were used f...

Abstract Background About 30 % of vegetables in China are produced intensively managed greenhouses comprising flood irrigation and extreme rates nitrogen fertilizers. Little is known about denitrification N losses. Methods Soil were measured by the acetylene inhibition technique applied to anaerobically incubated soil samples. Four different greenhouse management systems differentiated: Convent...