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Correlation and crowding measures: the fundamental lesson behind complex statistics
  1. Ellen J Weber
  1. Correspondence to Dr Ellen J Weber, Department of Emergency Medicine, University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143-0208, USA;{at}

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As someone who has taken basic statistics three times, I might be the least likely person to write this commentary highlighting the findings by Boyle and colleagues in their paper ‘Comparison of the International Crowding Measure in Emergency Departments (ICMED) and the National Emergency Department Overcrowding Score (NEDOCS) to measure emergency department crowding: pilot study’.1 But then, perhaps having someone as statistically ‘challenged’ as myself summarising what these authors have done will demonstrate that, despite a somewhat heady methods section, the underlying concepts are as simple to grasp as they are critically important.

The authors set out to compare the ability of the seven-point ICMED (sICMED) with the well-validated NEDOCS score, which originated in the USA, to reflect the sense of crowding and danger by senior physicians in England. To do this, one of the investigators collected data at four different EDs for …

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  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.

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