Using the Guttman Scale to Define and Estimate Measurement Error in Items over Time: The Case of Cognitive Decline and the Meaning of “Points Lost”

• Rochelle E. Tractenberg ,

  * E-mail: ret7@georgetown.edu

  Affiliations Departments of Neurology, Biostatistics, Bioinformatics & Biomathematics, and Psychiatry, Georgetown University Medical Center, Washington, District of Columbia, United States of America, Collaborative for Research on Outcomes and –Metrics, United States of America

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• Futoshi Yumoto,

  Affiliations Collaborative for Research on Outcomes and –Metrics, United States of America, University of Maryland University College, College Park, Maryland, United States of America

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• Paul S. Aisen,

  Affiliation Department of Neurology, University of California San Diego, La Jolla, California, United States of America

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• Jeffrey A. Kaye,

  Affiliation Layton Alzheimer's Disease Research Center, Oregon Health Sciences University, Portland, Oregon, United States of America

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• Robert J. Mislevy

  Affiliation Educational Testing Service, Princeton, New Jersey, United States of America

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