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Quality of Life Research

, Volume 22, Issue 8, pp 1999–2003 | Cite as

A new indicator for the measurement of change with ordinal scores

  • Mario Luiz Pinto Ferreira
  • Renan Moritz V. R. Almeida
  • Ronir Raggio Luiz
Article

Abstract

Background

Studies on how to better measure change have been published at least since the third decade of the last century, but no general indicator or strategy of measurement is currently agreed upon. The aim of this study is to propose a new indicator, the indicator of positive change, as an option for the assessment of change when ordinal scores are used in pretest and posttest designs.

Methods

The basic idea is to measure the proportion of possible (positive) change inside a group that can be attributed to an intervention. The approach is based on the joint distribution of the before and after scores (differences), represented by the cells (i, j) of a contingency table m × m (m is the number of classes of the ordinal measurement scale; i and j are the lines and columns of the table, respectively). By convention, higher classes are the most unfavorable on the scale such that subjects that improve “migrate” from the higher to the lower classes as a result of an intervention and vice versa.

Results

The introduced indicator offers a new strategy for the analysis of change when dealing with repeated measurements of the same subject, assuming that the measured variable is ordinal (e.g., clinician-rating scales).

Conclusion

The presented approach is easily interpretable and avoids the problems that arise, for instance, in those cases where a large concentration of high/low scores is present at the baseline.

Keywords

Measurement of change Ordinal scales Pre-post designs Clinician-rating scales 

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Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  • Mario Luiz Pinto Ferreira
    • 1
  • Renan Moritz V. R. Almeida
    • 1
  • Ronir Raggio Luiz
    • 1
  1. 1.Rio de JaneiroBrazil

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