Validity is the extent to which the inferences drawn from scores on a test or assessment can be justified empirically and theoretically. Establishing the validity of an assessment can be seen as an ongoing process of judgment, using different forms of evidence for substantiation. Traditionally validity has been defined within an evidential framework of three interrelated aspects: criterion, con...

Computers facilitate reasoning with complex data. We report a study where 195 students aged 12 to 15 years were presented with computer based tasks that require reasoning with multivariate data, together with paper based tasks from a well established scale of statistical literacy. All the tasks fitted well onto a single Rasch scale; computer tasks were cognitively more complex, but ranked only ...

BACKGROUND The Claim Evaluation Tools database contains multiple-choice items for measuring people's ability to apply the key concepts they need to know to be able to assess treatment claims. We assessed items from the database using Rasch analysis to develop an outcome measure to be used in two randomised trials in Uganda. Rasch analysis is a form of psychometric testing relying on Item Respon...

— Caussinus’s loglinear model of quasi symmetry has interesting connections with models for within-subject effects with repeated categorical measurement. For binary responses, Tjur (1982) showed that estimates of main effect parameters in the quasi-symmetry model are also conditional maximum likelihood estimates of item parameters for a fixed effects treatment of subject terms in the Rasch item...

BACKGROUND painDETECT (PD-Q) is a self-reported assessment of pain qualities developed as a screening tool for pain of neuropathic origin. Rasch analysis is a strategy for examining the measurement characteristics of a scale using a form of item response theory. We conducted a Rasch analysis to consider if the scoring and measurement properties of PD-Q would support its use as an outcome measur...

OBJECTIVE To develop a comprehensive measure of Early Physical Functioning (EPF) post-stroke quantified through Rasch analysis and conceptualized using the International Classification of Functioning Disability and Health (ICF). DESIGN An observational cohort study. SUBJECTS A cohort of 262 subjects (mean age 71.6 (standard deviation 12.5) years) hospitalized post-acute stroke. METHODS Fu...

BACKGROUND Economic environmental factors represent important barriers to participation and have deleterious effects on quality of life (QOL) in persons with spinal diseases (SpD). While economic factors are anchored in the International Classification of Functioning, Disability and Health, their influence on QOL and participation from patients' perspectives is an infrequent focus of research. ...

BACKGROUND AND PURPOSE Attempts have been made to provide guidelines for interpreting Barthel scores. We used a Rasch analysis to improve the measurement properties and clinical interpretability of the Barthel index score. METHODS A specific extension of Rasch model was used to identify items that preclude the summation of items and to improve the item rating scale by examining the scores on ...

BACKGROUND The aim of this study was to test the internal validity of the total Center for Epidemiologic Studies-Depression (CES-D) scale using Rasch analysis in a rheumatoid arthritis (RA) population. METHODS CES-D was administered to 157 patients with RA over three time points within a 12 month period. Rasch analysis was applied using RUMM2020 software to assess the overall fit of the model...

Traditional methods of developing tests have been driven by item content specification and have relied on the use of summed ordinal scores in an attempt to create a quantitative index of ability. There are fundamental problems with this approach to test development. The first problem is that the summing of qualitative ordinal counts to create a total score does not result in a number that is a ...