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BioMed Research International
Volume 2015, Article ID 270168, 7 pages
Research Article

Estimating Measurement Error of the Patient Activation Measure for Respondents with Partially Missing Data

1Linden Consulting Group, LLC, Ann Arbor, MI 48103, USA
2Department of Health Management & Policy, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA

Received 12 October 2014; Accepted 25 February 2015

Academic Editor: Daniel D. Reidpath

Copyright © 2015 Ariel Linden. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The patient activation measure (PAM) is an increasingly popular instrument used as the basis for interventions to improve patient engagement and as an outcome measure to assess intervention effect. However, a PAM score may be calculated when there are missing responses, which could lead to substantial measurement error. In this paper, measurement error is systematically estimated across the full possible range of missing items (one to twelve), using simulation in which populated items were randomly replaced with missing data for each of 1,138 complete surveys obtained in a randomized controlled trial. The PAM score was then calculated, followed by comparisons of overall simulated average mean, minimum, and maximum PAM scores to the true PAM score in order to assess the absolute percentage error (APE) for each comparison. With only one missing item, the average APE was 2.5% comparing the true PAM score to the simulated minimum score and 4.3% compared to the simulated maximum score. APEs increased with additional missing items, such that surveys with 12 missing items had average APEs of 29.7% (minimum) and 44.4% (maximum). Several suggestions and alternative approaches are offered that could be pursued to improve measurement accuracy when responses are missing.