Where data are to be pooled for international studies, analysis of DIF by culture is essential. Where DIF is observed, adjustments can be made to allow for cultural differences in outcome measurement.

Background and Purpose-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. Methods-One hundred three chronic (Ͼ6 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. Results-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. Key Words: arm Ⅲ disability evaluation Ⅲ rehabilitation Ⅲ stroke P oststroke hemiplegia is one of the most prevalent forms of motor disability, affecting approximately 1% of the population. 1 Although most current stroke survivors achieve an autonomous form of gait, a satisfactory recovery (if any) of the affected upper limb function is much more rare. Conclusions-TheAlthough several tests are available 2-4 for measuring upper limb function in terms of grip strength, dexterity, sensation, and performance in standardized manipulative tasks, the measurements are all made at the focal impairment level. 5 The actual disability, however, is far from linearly related to the underlying impairments. 6 It depends on complex interactions between upper limb function and compensatory behaviors of the person, such as using the unaffected limb or dividing complex movements into simpler ones. Moreover, the learning of new motor processes is influenced by the subject's motivational and emotional status, which is likely to be impaired by stroke. 7 Manual ability may be defined as the capacity to manage daily activities requiring the use of the upper limbs, whatever the strategies involved. Therefore, it should be measured per se and not simply inferred from focal impairments. Since it is a behavior, manual ability belongs to the domain of latent variables concealed within the person, such as pain, depression, and intelligence. The "amount" of manual ability can be inferred from observed activities and/or a patient's perceived difficul...

Background: A third version of the Spinal Cord Independence Measure (SCIM III), made up of three subscales, was formulated following comments by experts from several countries and Rasch analysis performed on the previous version. Objective: To examine the validity, reliability, and usefulness of SCIM III using Rasch analysis. Design: Multicenter cohort study. Setting: Thirteen spinal cord units in six countries from North America, Europe, and the Middle-East. Subjects: 425 patients with spinal cord lesions (SCL). Interventions: SCIM III assessments by professional staff members. Rasch analysis of admission scores. Main outcome measures: SCIM III subscale match between the distribution of item difficulty grades and the patient ability measurements; reliability of patient ability measures; fit of data to Rasch model requirements; unidimensionality of each subscale; hierarchical ordering of categories within items; differential item functioning across classes of patients and across countries. Results: Results supported the compatibility of the SCIM subscales with the stringent Rasch requirements. Average infit mean-square indices were 0.79-1.06; statistically distinct strata of abilities were 3 to 4; most thresholds between adjacent categories were properly ordered; item hierarchy was stable across most of the clinical subgroups and across countries. In a few items, however, misfit or category threshold disordering were found. Conclusions: The scores of each SCIM III subscale appear as a reliable and useful quantitative representation of a specific construct of independence after SCL. This justifies the use of SCIM in clinical research, including cross-cultural trials. The results also suggest that there is merit in further refining the scale.Spinal Cord (2007) 45, 275-291.

CIMT alone appears effective in modulating local excitability but not in removing the imbalance in transcallosal inhibition. Bihemispheric tDCS may achieve this goal and foster greater functional recovery.

Variables present in an individual, for example, independence, pain, balance, fatigue, depression and knowledge, cannot be measured directly (hence the term "latent" variables). They are usually assessed by measuring related behaviours, defined by sets of standardized items. The homogeneity of the different items, and proportionality of raw counts to measure, can only be postulated. In 1960 Georg Rasch proposed a statistical model that complied with the fundamental assumptions made in measurements in physical sciences. It allowed for the transformation of the cumulative raw scores (achieved by a subject across items, or by an item across subjects) into linear continuous measures of ability (for subjects) and difficulty (for items). These 2 parameters, only, govern the probability that "pass" rather than "fail" occurs. The discrepancies between model-expected scores (continuous between 0 and 1) and observed scores (discrete, either 0 or 1) provide indexes of inconsistency of individual subjects, items and classes of subjects. In subsequent years the same principles were extended to rating scales, with items graded on more than 2 levels, and to "many-facet" contexts where, beyond items and subjects, multiple raters, times of administration, etc. converge in determining the observed scores. Rasch modelling has increasing application in rehabilitation medicine. New scales with unprecedented metric validity (including internal consistency and reliability) can be built. Existing scales can be improved or rejected on a sound theoretical basis. In clinical trials the consistency and the linearity of measures of either subjects or raters can be validly matched with those of physical and chemical measures. The stability of the item difficulties across time, cultures, diagnostic groups and time of administration can be estimated, thus making it possible to compare homogeneous measures or foster diagnostic procedures on the reasons for differential item functioning.

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The TCT showed a good sensitivity to change in assessing recovery of stroke patients. The high item-total correlation and Cronbach's alpha value of the TCT suggest that there is one homogeneous construct underlying the item list. The TCT construct validity was confirmed by the correlation between this test and the FIM scores. TCT at admission predicted motFIM at discharge even better than motFIM at admission alone. Possibly, the TCT captures basic motor skills that foreshadow the recovery of more complex behavioral skills described by the FIM.

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