Quality of Life Research

, Volume 16, Supplement 1, pp 85–94 | Cite as

Linking scores from multiple health outcome instruments

  • Neil J. DoransEmail author
Original Paper


To the extent that outcomes of health assessment instruments are to be used interchangeably, the summary scores based on these outcomes need to be equated or made comparable. If the summary scores of different health assessment instruments are not equated, inferences based on them could be flawed. Ideally, summary scores would be comparable because of careful instrument design. In practice, that rarely happens. Statistical intervention is usually needed. This article addresses key questions associated with the linking of summary scores of health outcomes. What is meant by outcome linking and equating? How does equating differ from other types of linking? What common data collection designs are used to capture data for outcomes linking? What are some of the standard statistical procedures used to link outcomes directly? What assumptions do they make? What role does IRT play in linking outcomes? What assumptions do IRT methods make? This article makes a distinction between direct statistical adjustments of summary score distributions, and indirect procedures based on psychometric models of items or questions.


Linking Equating Cross-walk table Concordance Calibration IRT 



Neil J. Dorans is a Distinguished Presidential Appointee in the Center for Statistical Theory and Practice of the Research and Development Division at Educational Testing Service. The opinions expressed in this paper are his alone and do not represent the opinions of Educational Testing Service. The comments of colleagues at ETS, Dr. C-H Chang of Northwestern University, Dr. Ron D. Hays of UCLA and Dr. Bryce Reeve of the National Institutes of Health were helpful in preparing this paper, as were those of three reviewers.


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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  1. 1.Center for Statistical Theory and Practice, Research and Development DivisionEducational Testing ServicePrincetonUSA

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