OBJECTIVE To develop a hierarchical scale that measures activity limitations in climbing stairs in patients with lower-extremity disorders living at home. DESIGN Cross-sectional study with Mokken scale analysis of 15 dichotomous items. SETTING Outpatient clinics of secondary and tertiary care centers. PARTICIPANTS Patients (N=759; mean age +/- standard deviation, 59.8+/-15.0y; 48% men) li...

PURPOSE The visual functioning index (VFI) was one of the first questionnaires developed using classical test theory to assess outcomes of cataract surgery. However, it was not Rasch-validated. The objective of this study was to examine the psychometric properties of the VFI using Rasch analysis in patients with cataract. METHODS The 11-item VFI was self-administered to 243 patients (mean age...

This study uses simulated data to compare two methods of calculating Differential Test Functioning (DTF): Raju’s DFIT, a parametric method that measures the squared difference between two Test Characteristic Curves (Raju, van der Linden & Fleer, 1995), and a variance estimator based on the Mantel-Haenszel/Liu-Agresti method, a non-parametric method enabled in the DIFAS (Penfield, 2005) program....

BACKGROUND To develop and validate an item bank to measure mobility in older people in primary care and to analyse differential item functioning (DIF) and differential bundle functioning (DBF) by sex. METHODS A pool of 48 mobility items was administered by interview to 593 older people attending primary health care practices. The pool contained four domains based on the International Classifi...

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...

BACKGROUND Quality of life (QoL) questionnaires are desirable for clinical practice but can be time-consuming to administer and interpret, making their widespread adoption difficult. OBJECTIVE Our aim was to assess the performance of the World Health Organization Quality of Life (WHOQOL)-100 questionnaire as four item banks to facilitate adaptive testing using simulated computer adaptive test...