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The meaning of variation to healthcare managers, clinical and health-services researchers, and individual patients
  1. Duncan Neuhauser1,
  2. Lloyd Provost2,
  3. Bo Bergman3
  1. 1Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, Ohio, USA
  2. 2Associates in Process Improvement, Austin, Texas, USA
  3. 3Centre for Health Improvement, Chalmers University of Technology, Gothenburg, Sweden
  1. Correspondence to Charles Elton Blanchard Professor Duncan Neuhauser, Department of Epidemiology and Biostatistics, Medical School, Case Western Reserve University, 10900 Euclid Ave, Cleveland Ohio 44106-4249, USA; dvn{at}


Healthcare managers, clinical researchers and individual patients (and their physicians) manage variation differently to achieve different ends. First, managers are primarily concerned with the performance of care processes over time. Their time horizon is relatively short, and the improvements they are concerned with are pragmatic and ‘holistic.’ Their goal is to create processes that are stable and effective. The analytical techniques of statistical process control effectively reflect these concerns. Second, clinical and health-services researchers are interested in the effectiveness of care and the generalisability of findings. They seek to control variation by their study design methods. Their primary question is: ‘Does A cause B, everything else being equal?’ Consequently, randomised controlled trials and regression models are the research methods of choice. The focus of this reductionist approach is on the ‘average patient’ in the group being observed rather than the individual patient working with the individual care provider. Third, individual patients are primarily concerned with the nature and quality of their own care and clinical outcomes. They and their care providers are not primarily seeking to generalise beyond the unique individual. We propose that the gold standard for helping individual patients with chronic conditions should be longitudinal factorial design of trials with individual patients. Understanding how these three groups deal differently with variation can help appreciate these three approaches.

  • Control charts
  • evidence-based medicine
  • quality of care
  • statistical process control

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  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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