Item Difficulty Hierarchy Research Articles

Measuring sexual risk for HIV: a Rasch scaling approach.

In this study, we developed an HIV transmission risk scale and examined its psychometric properties using data on sexual behavior obtained from a probability sample of adult men who have sex with men living in Chicago. We used Messick's (Am Psychol 50:741-749, 1995) conceptualization of unified validity theory to organize the psychometric properties of data. Evidence related to scale content was investigated via Rasch item fit statistics, point-measure correlations, and expert evaluation. The substantive aspect of validity was addressed by interpreting the meaningfulness of the item difficulty hierarchy (continuum of risky behaviors) and assessment of person fit. The structural aspect of validity was assessed using Rasch item fit statistics, principal component analysis of standardized residuals, and other residual analyses. The generalizability aspect of validity was investigated via internal consistency reliability estimates for both items and persons, and aspects of external validity were addressed by examining between-group differences with respect to levels of risky behavior. Applications and suggested future studies are discussed.

Validation of the orthotics and prosthetics user survey upper extremity functional status module in people with unilateral upper limb amputation

To evaluate the measurement properties of the Upper Extremity Functional Status module of the Orthotics and Prosthetics User Survey (OPUS). Methodological research on an outcome measure administered by clinical interview. A convenience sample of 61 adults who had unilateral upper limb amputations and completed rehabilitation at the Institute for Rehabilitation in Ljubljana, Slovenia, at least one year prior to interview. Thirty-four patients had undergone amputation of the dominant hand. Four patients did not use a prosthesis. Rating scale analysis (Rasch model) was used to evaluate functioning of the rating scale categories, the validity of the measure by examining fit of items to the latent trait, and the hierarchy of item difficulties compared with expectations of the construct. Rasch analysis allowed us to improve the Upper Extremity Functional Status by rescoring to reduce the response categories from 5 to 4, and identifying 19 of 23 items that are useful to measure upper extremity function. The results allow us to have high confidence in the consistency of both person-ability and item-difficulty estimates. This revised Upper Extremity Functional Status is a promising instrument to measure the degree of manual functioning after a unilateral upper limb amputation.

Utilizing Rasch measurement models to develop a computer adaptive self-report of walking, climbing, and running

Purpose. The purpose of this paper is to show how the Rasch model can be used to develop a computer adaptive self-report of walking, climbing, and running.Method. Our instrument development work on the walking/climbing/running construct of the ICF Activity Measure was used to show how to develop a computer adaptive test (CAT). Fit of the items to the Rasch model and validation of the item difficulty hierarchy was accomplished using Winsteps software. Standard error was used as a stopping rule for the CAT. Finally, person abilities were connected to items difficulties using Rasch analysis ‘maps’.Results. All but the walking one mile item fit the Rasch measurement model. A CAT was developed which selectively presented items based on the last calibrated person ability measure and was designed to stop when standard error decreased to a pre-set criterion. Finally, person ability measures were connected to the ability to perform specific walking/climbing/running activities using Rasch maps.Conclusions. Rasch measurement models can be useful in developing CAT measures for rehabilitation and disability. In addition to CATs reducing respondent burden, the connection of person measures to item difficulties may be important for the clinical interpretation of measures.

ACTIVLIM: A Rasch-built measure of activity limitations in children and adults with neuromuscular disorders

A common measure of activity limitations for both children and adults with neuromuscular disorders was developed using the Rasch model. A self-reported questionnaire containing daily activities was submitted to 245 adult patients and to the parents of 124 affected children from the two major Belgian communities. They were asked to provide their perceived difficulty in performing daily activities on a three-level scale. The 22 items of the final scale define a unidimensional and linear measure of activity limitations and show a continuous progression in their difficulty. The item difficulty hierarchy is invariant with regard to the diagnosis, community, gender and age. The scale exhibits a good precision, since the 22 items are well targeted on our sample ( r = 0.96); furthermore, it is reproducible over time (ICC = 0.93). The patients’ measures are related to the Functional Independence Measure motor score ( ρ = 0.85), to the Brooke ( ρ = −0.63) grade and to the Vignos ( ρ = −0.83) grade.

Developing Meaningful Fear of Falling Measures for Community Dwelling Elderly

The objective of this study is to demonstrate how a Rasch analytic approach can be used to create fear of falling measures that remain connected to the meaningful descriptions provided by the instrument items. The University of Illinois at Chicago Fear of Falling Measure was developed using focus groups and consists of 19 common activities designed to represent an increasing level of concern about falling among older adults. Rasch analysis of responses from 106 community dwelling elderly revealed that the two middle rating scale categories (a little worried and moderately worried) were not being used in the expected fashion. After modification of the rating scale, Rasch analysis showed that the three items causing the least worry (get dressed, get on/off toilet, and get in/out of bed) were statistically erratic. Final analysis demonstrated that the remaining 16 items represented a unidimensional construct that, in general, supported the original expected item difficulty hierarchy. Because person and item measures were calibrated on the same linear scale person measures are translatable to item descriptions. This connection provides meaning to the numeric values obtained from the instrument and provides a basis for setting clinically relevant criteria for interventions.

The ABILHAND questionnaire as a measure of manual ability in chronic stroke patients: Rasch-based validation and relationship to upper limb impairment.

Chronic hemiparetic patients often retain the ability to manage activities requiring both hands, either through the use of the affected arm or compensation with the unaffected limb. A measure of this overall ability was developed by adapting and validating the ABILHAND questionnaire through the Rasch measurement model. ABILHAND measures the patient's perceived difficulty in performing everyday manual activities. One hundred three chronic (>6 months) stroke outpatients (62% men; mean age, 63 years) were assessed (74 in Belgium, 29 in Italy). They lived at home and walked independently and were screened for the absence of major cognitive deficits (dementia, aphasia, hemineglect). The patients were administered the ABILHAND questionnaire, the Brunnström upper limb motricity test, the box-and-block manual dexterity test, the Semmes-Weinstein tactile sensation test, and the Geriatric Depression Scale. The brain lesion type and site were recorded. ABILHAND results were analyzed with the use of Winsteps Rasch software. The Rasch refinement of ABILHAND led to a change from the original unimanual and bimanual 56-item, 4-level scale to a bimanual 23-item, 3-level scale. The resulting ability scale had sufficient sensitivity to be clinically useful. Rasch reliability was 0.90, and the item-difficulty hierarchy was stable across demographic and clinical subgroups. Grip strength, motricity, dexterity, and depression were significantly correlated with the ABILHAND measures. The ABILHAND questionnaire results in a valid person-centered measure of manual ability in everyday activities. The stability of the item-difficulty hierarchy across different patient classes further supports the clinical application of the scale.

Construct Validity of the Sensory Integration and Praxis Tests

The purpose of this study was to examine the construct validity of the praxis tests of the Sensory Integration and Praxis Tests (SIPT) and to determine whether the practic component of sensory integration-based developmental dyspraxia is a unitary or a multidimensional disorder. Developmental dyspraxia is an impaired ability to plan and execute skilled or nonhabitual motor tasks; however, its underlying cause, or even whether praxis is a unitary or multidimensional function, is not yet clarified. In this study, the Rasch model of measurement (Linacre, 1989; Wright & Masters, 1982; Wright & Stone, 1979) was used to explore the underlying construct of developmental dyspraxia. The Rasch model was chosen because its use enabled us to (a) confirm goodness-of-fit of individual items within SIPT praxis tests and (b) examine the hierarchical structure of item difficulties. The data included the raw scores of the SIPT praxis tests of 210 subjects from Canada and the United States. The results of the Rasch analyses revealed that each of these five SIPT praxis tests measures a single, unidimensional construct. When the items from the five tests were combined to create a single 117-item test, the items continued to define a single practic function. This indicates that a unitary practic component underlies both bilateral integration and sequencing deficits and somatodyspraxia. Finally, examination of the hierarchy of item difficulties resulted in recommendations for the development of a single screening test for developmental dyspraxia. The implications of these results for clinical practice and future research are discussed.