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Multiple Sclerosis
Construct specification equations are developed by regression analysis of item played by rating scales must increase, thus neurologists who are also journal
locations (here text difficulty) on selected item characteristics (here word editors, reviewers, and involved with grant-giving bodies should build links,
frequency and sentence length). They afford a test of fit between scale- or have direct access to, people with expertise in rating scale development
generated observations and theory.
56
In essence, the greater the proportion and evaluation. Third, neurologists already involved in rating scale research
of variation in item location explained by the selected item characteristics, the should begin to aspire to new methodologies, such as Rasch measurement
greater the support for the proposed construct theory, the greater and theory-referenced measurement.
the evidence for scale validity, and the more clinically meaningful the
interpretation of person locations. Moreover, construct specification equations We hope the arguments in this article have helped to illustrate some of the
allow different construct theories to be articulated and challenged, thus current problems and potential solutions in using rating scales in clinical
enabling dynamic interplay between theory and scale
42
and a thorough studies of neurology. Although we have only touched upon the value of
investigation of individual items to aid item development and selection. new psychometric methods and theory-referenced measurement, we feel
that these new avenues have much to offer all neurological outcome
So What Next? measurement, state-of-the-art clinical trials, and, most importantly, the
There are three key steps neurologists can take right now to help improve individual patients that neurologists treat. We hope that neurologists
the rating scales used in neurology. First, more neurologists need to be interested in conducting rating scale research will use this article as a
formally trained in rating scale methods to ensure that health measurement springboard to finding out more about new developments in this rapidly
develops clinically meaningful scales. Second, awareness of the critical role growing area. ■
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18 US NEUROLOGY
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