caa a22 4500 60546622X CHVBK 20210128100306.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s00769-015-1113-8 doi (NATIONALLICENCE)springer-10.1007/s00769-015-1113-8 A new approach to calculating the Sigma Metric in clinical laboratories [Elektronische Daten] [Abdurrahman Coskun, Mustafa Serteser, Meltem Kilercik, Fehime Aksungar, Ibrahim Unsal] In clinical laboratories, the performance of a process as Sigma Metric (SM) is calculated by the equations derived by Westgard. In the present study, we found that the Westgard equations do not reflect the real performance of the process and that the SM calculated using these equations is lower than the real SM. We measured the substance concentration of ten analytes (glucose, urea, creatinine, cholesterol, calcium, magnesium, phosphorus, LDH, sodium, and potassium) in serum and calculated the SM for each using the Westgard equations and z transformations. The SM values for the same measurand using the Westgard equations based on either the absolute or the relative (percentage) results were not equal to each other, and those related to calcium and sodium were even lower than 0. The SM obtained from the z transformation was higher than that from the Westgard equations, and none were lower than 0. We concluded that the equations suggested by Westgard to calculate the SM do not cover all of the data produced by the process and do not reflect reality. From our research, the z transformation was the optimum method of calculating the actual SM for the process. Springer-Verlag Berlin Heidelberg, 2015 Bias nationallicence Sigma Metric nationallicence Six Sigma nationallicence Tolerance limit nationallicence z transformation nationallicence Coskun Abdurrahman Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut Serteser Mustafa Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut Kilercik Meltem Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut Aksungar Fehime Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut Unsal Ibrahim Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut Accreditation and Quality Assurance Springer Berlin Heidelberg 20/2(2015-04-01), 147-152 0949-1775 20:2<147 2015 20 769 https://doi.org/10.1007/s00769-015-1113-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00769-015-1113-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Coskun Abdurrahman Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut NATIONALLICENCE 700 1- Serteser Mustafa Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut NATIONALLICENCE 700 1- Kilercik Meltem Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut NATIONALLICENCE 700 1- Aksungar Fehime Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut NATIONALLICENCE 700 1- Unsal Ibrahim Department of Medical Biochemistry, School of Medicine, Acibadem University, Atasehir, Istanbul, Turkey aut NATIONALLICENCE 773 0- Accreditation and Quality Assurance Springer Berlin Heidelberg 20/2(2015-04-01), 147-152 0949-1775 20:2<147 2015 20 769