Sigma metric revisited: True known mistakes

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BIOCHEMIA MEDICA, vol.29, no.1, 2019 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 29 Issue: 1
  • Publication Date: 2019
  • Doi Number: 10.11613/bm.2019.010902
  • Journal Name: BIOCHEMIA MEDICA
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED)
  • Keywords: laboratory error, normal distribution, sigma metric, Six Sigma, uniform distribution
  • Acibadem Mehmet Ali Aydinlar University Affiliated: Yes


Six Sigma methodology has been used successfully in industry since the mid-1980s. Unfortunately, the same success has not been achieved in laboratory medicine. In this case, although the multidisciplinary structure of laboratory medicine is an important factor, the concept and statistical principles of Six Sigma have not been transferred correctly from industry to laboratory medicine. Furthermore, the performance of instruments and methods used in laboratory medicine is calculated by a modified equation that produces a value lower than the actual level. This causes unnecessary, increasing pressure on manufacturers in the market. We concluded that accurate implementation of the sigma metric in laboratory medicine is essential to protect both manufacturers by calculating the actual performance level of instruments, and patients by calculating the actual error rates.