Statistical Question

Normal ranges

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f1343 (Published 8 March 2013)
Cite this as: BMJ 2013;346:f1343

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  1. Philip Sedgwick, reader in medical statistics and medical education1
  1. 1Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London, UK
  1. p.sedgwick{at}sgul.ac.uk

Researchers used cardiac magnetic radial images with radial long axis orientation to establish normal ranges of left ventricular function. Participants were 40 apparently healthy people (20 men, average age 32.3 years, age range 19-58; 20 women, average age 37.4 years, age range 21-54). Investigations were conducted using a steady state free precession pulse sequence.1

Measurements of left ventricular function included end diastolic volume adjusted for body surface area. Men had a sample mean volume of 90.9 mL/m2 (standard deviation 14.3) and women 80.7 mL/m2 (11.2). Normal ranges for left ventricular volume were calculated as two standard deviations either side of the sample mean. The normal ranges for left ventricular end diastolic volume were 62.3-119.5 mL/m2 for men and 58.3-103.1 mL/m2 for women.

Which of the following statements, if any, are true?

  • a) Any …

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