Back to Journals » Patient Related Outcome Measures » Volume 1

Is less more? A preliminary investigation of the number of response categories in self-reported pain

Authors Cook K, Cella D, Boespflug EL, Amtmann D

Published 14 May 2010 Volume 2010:1 Pages 9—18


Review by Single-blind

Peer reviewer comments 2

Karon F Cook1, David Cella2, Erin L Boespflug1, Dagmar Amtmann1

1Department of Rehabilitation Medicine, University of Washington, Seattle, WA; 2Department of Medical Social Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA

Abstract: The purpose of this study was to conduct a preliminary investigation of the number of response options for self-reports of pain interference. Responses to interference items of the 11-category Brief Pain Inventory (BPI) were obtained in a sample of 434 persons from two sites and modeled using the partial credit model. In successive calibrations, response categories were collapsed and new scores were generated. Scores based on two to three categories produced poor results. Four to five categories yielded better results. However, scoring using more than five categories did not appreciably improve the reliability, person separation, or validity of scores. These results suggest that fewer response categories—as few as five or six–may function as well as the 11 response categories that are conventionally used. The results are preliminary since the number of response categories actually presented was not manipulated in the study design. Future research should compare the reliability and validity of scores based on the BPI interference items when items are presented with the conventionally 11-response format, versus presentation with fewer response options.
Keywords: psychometrics, outcomes, quality of life, measurement, pain

Creative Commons License This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.

Download Article [PDF]  View Full Text [HTML][Machine readable]