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Rating scales are employed as a means of extracting more information out of an item than would be obtained from a mere "yes/no", "right/wrong" or other dichotomy. But does this additional information increase measurement accuracy and precision? Eight guidelines are suggested to aid the analyst in optimizing the manner in which rating scales categories(More)
Eight guidelines are suggested to aid the analyst in investigating whether rating scales categories are cooperating to produce observations on which valid measurement can be based. These guidelines are presented within the context of Rasch analysis. They address features of rating-scale-based data such as category frequency, ordering, rating-to-measure(More)
Factor analysis is a powerful technique for investigating multidimensionality in observational data, but it fails to construct interval measures. Rasch analysis constructs interval measures, but only indirectly flags the presence of multidimensional structures. Simulation studies indicate that, for responses to complete tests, construction of Rasch measures(More)
Building on Wright and Masters (1982), several Rasch estimation methods are briefly described, including Marginal Maximum Likelihood Estimation (MMLE) and minimum chi-square methods. General attributes of Rasch estimation algorithms are discussed, including the handling of missing data, precision and accuracy, estimate consistency, bias and symmetry.(More)
Quantitative observations are based on counting observed events or levels of performance. Meaningful measurement is based on the arithmetical properties of interval scales. The Rasch measurement model provides the necessary and sufficient means to transform ordinal counts into linear measures. Imperfect unidimensionality and other threats to linear(More)
OBJECTIVES To develop a new rating scale for measuring the health impact of cervical dystonia (CD) that includes patients' perceptions and complements existing observer dependent clinician rating scales. METHODS Scale development was in three stages. In Stage 1, a large pool of items was generated from patient interviews (n = 25), expert opinion, and(More)
The Visual Analog Scale (VAS) can be used to record subjectively experienced pain in different situations (items). By a mathematical method, the Rasch analysis, the original VAS recordings can be converted to an interval scale. Forty women with Patellofemoral Pain Syndrome (PFPS) reported their pain on the VAS from 12 different situations (items) before and(More)
Theoretical and practical aspects of several methods for the construction of linear measures from rank-ordered data are presented. The final partial-rankings of 356 professional golfers participating in 47 stroke-play tournaments are used for illustration. The methods include decomposing the rankings into independent paired comparisons without ties, into(More)
The Functional Independence Measure (FIM) records the severity of disability of rehabilitation patients. The necessarily curvilinear relationship between the finite range of recorded FIM raw scores and the conceptually infinite range of additive disability measures is resolved through Rasch analysis. The analysis of admission and discharge FIM ratings of(More)