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...

PURPOSE To assess and re-engineer the Vision Core Measure 1 (VCM1) questionnaire in low vision (LV) and cataract participants using Rasch analysis. METHODS 295 participants drawn from a low vision clinic and 181 from a cataract surgery waiting list completed the 10-item VCM1. Unidimensionality, item fit to the model, response category performance, differential item functioning (DIF) and targe...

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...

In the social sciences, performance of two groups is frequently compared based on a cognitive test involving binary items. Item response models are often utilized for comparing groups. However, presence differential item functioning (DIF) can impact group comparisons. order to avoid biased estimation groups, appropriate statistical methods handling required. This article compares performance-re...

Background The aim of this study was to test the General Oral Health Assessment Index Questionnaire (GOHAI) items for differential item functioning (DIF) according to demographic characteristics (gender, age) and mental health status (schizophrenic disorders versus general population) using Rasch analysis. Methods This is a cross-sectional study using aggregated baseline data from a validatio...

The use of longitudinal data for studying cross-time changes is built on the key assumption that properties (e.g., slopes and intercepts) of the repeatedly-used items remain unchanged over time. True changes in the latent variables are indistinguishable from item-level changes when items exhibit differential item functioning (DIF) across time points. To date, no research has extended the modifi...

There has been some concern that participation in an intervention and exposure to a measurement instrument can change participants' interpretation of the items on a self-report questionnaire thereby distorting subsequent responses and biasing results. Differential item functioning (DIF) analysis using item response modeling can ascertain possible differences in item interpretation by testing fo...

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...