World Health Organization. Diagnostics – WHO Health Topic page. Geneva: World Health Organization. 2025 [cited 2025 Dec 22]. Available from: https://www.who.int/health-topics/diagnostics

Oosterhuis W, Bayat H, Armbruster D, Coskun A, Freeman KP, Kallner A et al. The use of error and uncertainty methods in the medical laboratory. Clin Chem Lab Med. 2018;56(2):209–219. Available from: https://doi.org/10.1515/cclm-2017-0341

Westgard JO, Westgard SA. Measuring Analytical Quality: Total Analytical Error Versus Measurement Uncertainty. Clinics in Laboratory Medicine. 2017;37(1):1–13. Available from: https://doi.org/10.1016/j.cll.2016.09.001

White GH. Hitchhiker’s Guide to Measurement Uncertainty in Clinical Laboratories. APFCB News. 2022;1(2):68–75. Available from: https://doi.org/10.62772/APFCB-News.2022.2.1

International Organization for Standardization. Medical Laboratories — Requirements for quality and competence. 4th ed. Geneva: ISO; 2022.

Google Scholar 

Westgard JO. Statistical Quality Control Procedures. Clinics in Laboratory Medicine. 2013;33(1):111–124. Available from: https://doi.org/10.1016/j.cll.2012.10.004

Coskun A, Theodorsson E, Oosterhuis WP, Sandberg S, European Federation of Clinical Chemistry and Laboratory Medicine Task and Finish Group on Practical Approach to Measurement Uncertainty. Measurement uncertainty for practical use. Clin Chim Acta. 2022;531:352–360.Available from: https://doi.org/10.1016/j.cca.2022.04.1003

Westgard S, Bayat H, Westgard JO. Analytical sigma metrics: A review of six sigma implementation tools for medical laboratories. Biochem Med (Zagreb). 2018;28(2):020502. Available from: https://doi.org/10.11613/BM.2018.020502

Westgard JO. Useful measures and models for analytical quality management in medical laboratories. Clin Chem Lab Med. 2016;54(2):223–233. Available from: https://doi.org/10.1515/cclm-2015-0710

Bhattacharjee D, Ghosh B, Chaudhuri AR, Chakrabarty S, Naskar S, Mukherjee K. Sigma metrics application in clinical biochemistry: Practical requisite or unfeasible misadventure. Asian J Med Sci. 2024;15(6):29–34. Available from: https://doi.org/10.71152/ajms.v15i6.547

Giannoli JM, Vassault A, Carobene A, Liaudet AP, Blasutig IM, Dabla PK, etal. IFCC Laboratory Medicine Task Force on Global Lab Quality (TF-GLQ). Ensuring internal quality control practices in medical laboratories: IFCC recommendations for practical applications based on ISO 15189:2022 Clin Chim Acta. 2025:571:120240. Available from: https://doi.org/10.1016/j.cca.2025.120240

Westgard SA. Utilizing global data to estimate analytical performance on the Sigma scale: A global comparative analysis of methods, instruments, and manufacturers through external quality assurance and proficiency testing programs. Clin Biochem. 2016;49(9):699–707. Available from: https://doi.org/10.1016/j.clinbiochem.2016.02.013

Sharma S, Agarwal R. Quality management in laboratory. In: Sharma S, Agarwal R, editors. Excellence in clinical laboratory operations: A comprehensive guide to quality practices and reliable results. 1st ed. New Delhi: Ahuja Publishing House; 2025. pp. 89–128.

Google Scholar 

Westgard JO. Internal quality control: planning and implementation strategies. Ann Clin Biochem. 2003;40(Pt 6):593–611. Available from: https://doi.org/10.1258/000456303770367199

Ricos C, Fernandez-Calle P, Perich C, Westgard JO. Internal quality control - past, present and future trends. Adv Lab Med. 2022;3(3):243–262. Available from: https://doi.org/10.1515/almed-2022-0029

Farrance I, Badrick T, Sikaris KA. Uncertainty in measurement and total error-Are they so incompatible? Clin Chem Lab Med. 2016;54(8):1309–1311. Available from: https://doi.org/10.1515/cclm-2016-0314

Panteghini M, Sandberg S. Total error vs. measurement uncertainty: The match continues. Clinical Chemistry and Laboratory Medicine. 2016;54(2):195–196. Available from: https://doi.org/10.1515/cclm-2015-1036

Kallner A. Is the combination of trueness and precision in one expression meaningful? on the use of total error and uncertainty in clinical chemistry. Clin Chem Lab Med. 2016;54(8):1291–1297. Available from: https://doi.org/10.1515/cclm-2015-0975

Haeckel R, Wosniok W, Streichert T. Optimizing the use of the state-of-the-art performance criteria. Clinical Chemistry and Laboratory, Medicine, CCLM, Haeckel R, Wosniok W, Postma T. Quantity quotient report- ing. Comparison of various models. Clin Chem Lab Med 2015;53:1921–6, Haeckel R, Wosniok W, Postma T. Quantity quotient report- ing. Comparison of various models. Clin Chem Lab Med 2015;53:1921–6.

Karadag C, Demirel N. Total Analytical Error and Measurement Uncertainty for Analytical Performance Evaluation and Determination of Gray Zones of Glucose Critical Value Limits. Lab Med. 2023;54 (2):153–159. Available from: https://doi.org/10.1093/labmed/lmac077

Joint Committee For Guides In. Evaluation of measurement data — Guide to the expression of uncertainty in measurement. Int Organ Stand Geneva ISBN. 2008;50 September. Available from: https://www.bipm.org/documents/20126/2071204/JCGM_100_2008_E.pdf

NABL 112 A. Specific Criteria for Accreditation of Medical Laboratories. National Accreditation Board for Testing and Calibration Laboratories.:issue 01. Available from: www.nablindia.org

ISO/IEC 17043. 2023. Conformity assessment- General requirements for competence of proficiency testing Providers. 2nd edn. 2023. Available from: https://www.iso.org/obp/ui/en/#iso:std:iso-iec:17043:ed-2:v1:en

White GH, Farrance I, AACB Uncertainty of Measurement Working Group. Uncertainty of measurement in quantitative medical testing: a laboratory implementation guide. Clin Biochem Rev. 2004;25(4):S1–24.

PubMed  PubMed Central  CAS  Google Scholar 

Westgard QC. 2025 CLIA Acceptance Limits for Proficiency Testing. Available from: https://westgard.com/clia-a-quality/quality-requirements/2024-clia-requirements.html

Gu H, Lee J, Hong J, Lee W, Yun YM, Chun S, et al. Practical considerations for clinical laboratories in Top-down approach for assessing the measurement uncertainty of clinical chemistry analytes. Ann Lab Med. 2022;42(6):630–7. https://doi.org/10.3343/alm.2022.42.6.630.

Article  PubMed  PubMed Central  Google Scholar 

Ceriotti F. Deriving proper measurement uncertainty from Internal Quality Control data: An impossible mission? Clinical Biochemistry. 2018;57:37–40. Available from: https://doi.org/10.1016/j.clinbiochem.2018.03.019

Jassam N. Quality control in the age of risk management. Ann Clin Biochem Int J Lab Med. 2014;51(6) 719–720. Available from: https://doi.org/10.1177/0004563214524881

Haeckel R, Wosniok W, Gurr E, Peil B. Permissible limits for uncertainty of measurement in laboratory medicine. Clinical Chemistry and Laboratory Medicine (CCLM). 2015;53 (8): 1161–1171.Available from: https://doi.org/10.1515/cclm-2014-0874

Oosterhuis WP. Gross overestimation of total allowable error based on biological variation. Clinical Chemistry. 2011;57(9):1334–1336. Available from: https://doi.org/10.1373/clinchem.2011.165308

Coskun A. Bias in Laboratory Medicine: The Dark Side of the Moon. Ann Lab Med. 2024;44(1):6–20. Available from: https://doi.org/10.3343/alm.2024.44.1.6

Clinical and Laboratory Standards Institute (CLSI). EP46 - Determining Allowable Total Error Goals and Limits for Quantitative Medical Laboratory Measurement Procedures. 1st ed. CLSI. 2025. Available from: https://clsi.org/shop/standards/ep46-plus/

Cevlik T, Haklar G. Six Sigma evaluation of 17 biochemistry parameters using bias calculated from internal quality control and external quality assurance data. J Med Biochem. 2024;43(1):43–49. Available from: https://doi.org/10.5937/jomb0-43052