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...

The Gram-negative soil bacterium Myxococcus xanthus has a complex life cycle that involves vegetative growth and, when nutrients are limiting, formation of spore-containing fruiting bodies. The progression of the developmental cycle depends in part upon the ability of M. xanthus cells to sense and respond to their environment and to coordinate two different motility systems to achieve directed ...

Many Prolog programs are unnecessarily impure because of inadequate means to express syntactic inequality. While the frequently provided built-in dif/2 is able to correctly describe expected answers, its direct use in programs often leads to overly complex and inefficient definitions — mainly due to the lack of adequate indexing mechanisms. We propose to overcome these problems by using a new p...

The reliability and validity of the six traits comprising High Potential Trait Indicator (HPTi) were evaluated using Rasch analysis. Focus was designated to unidimensionality local independence each subscale; fit model; person separation; differential item functioning (DIF). Secondary data, obtained from intellectual property rights holder Thomas International, used for analysis with a sample 1...

Purpose To assess whether a panel of serum pemphigoid autoantibody tests could be used to confirm an immunopathologic diagnosis mucous membrane (MMP) in direct immunofluorescent negative (DIF–) MMP patients. Design Prospective cross-sectional study. Participants Seventy-six patients with multisite 45 matched control participants. Methods Enzyme-linked immunosorbent assays (ELISAs) for BP180 and...

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...

INTRODUCTION There are several studies showing the presence of Differential Item Functioning (DIF) in some items of the Beck Depression Inventory (BDI), when comparing men and women. The presence of a large number of items with DIF in BDI is a severe threat to the validity of measurement of the intensity of depressive symptoms obtained by Item Response Theory (IRT) and to the conclusions based ...

Differential item functioning (DIF) can lead to an unfair advantage or disadvantage for certain subgroups in educational and psychological testing. Therefore, a variety of statistical methods has been suggested for detecting DIF in the Rasch model. Most of these methods are designed for the comparison of pre-specified focal and reference groups, such as males and females. Latent class approache...