Abstract
The inter-comparison exercise results carried as a part of external quality control helps in establishing the accuracy and uncertainty of the method and the measurement system. The performance evaluation is based on the statistical performance indicators such as precision, trueness, relative bias and z-score. Z-score is used for scaling the difference between a participant’s result and the assigned value for the concentration of the radio-analyte. It allows interpreting the data with different means and standard deviations and placing them on a common scale. This standard scale was used to compare result of the proficiency test made over the years for different radionuclides in matrices such as water, soil, sediment, seaweed, rice grain, having variable mean and standard deviation.
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References
ISO/IEC 17025, General requirements for competence of testing and calibration laboratories, ISO, Geneva, 2017
S. K. Jha, Vandana Pulhani, S. J. Sartandel, Sanu S. Raj, Sugandhi Suresh, Madhuparna Dutta, Moushumi Chaudhury, Rupali Karpe, V. M. Joshi, R. H. Pillay and R. M. Tripathi, Lessons learnt from participation in international intercomparison exercise for environmental radioactivity measurement, BARC External Report BARC/2016/E009, 2016.
ISO 13528, Statistical methods for use in proficiency testing by inter-laboratory comparisons, ISO, Geneva, 2015.
W.P. Cofino and D.E. Wells, Design and evaluation of the QUASIMEME inter-laboratory performance studies: a test case for robust statistics. Mar. Pollut. Bull., 29 (1994) 149–158.
Michael Thompson, Stephen L.R.. Ellison and Roger Wood, The International Harmonized Protocol for the proficiency testing of analytical chemistry laboratories. Pure Appl. Chem., 78(1) (2006) 145–196.
A. Aminot, J. De Boer, W. Cofino, D. Kirkwood, B. Pederson and D.E. Wells, Report on the Laboratory Performance Studies 1994, QUASIMEME Scientific Group, Aberdeen, 1995.
D.E. Wells, A. Aminot, W. Jacob de Boer, D. Kirkwood. Cofino and B. Pedersen, A review of the achievements of the EU Project QUASIMEME 1993–1996. Mar. Pollut. Bull., 35(1–6) (1997) 3–17.
Mike J. Gardner, Judy E. Dobson, Andy H. Griffiths, Mike A. Jessep and Jim E. Ravenscroft, An overview of the UK national marine analytical quality control (NMAQC) scheme and its links with QUASIMEME. Mar. Pollut. Bullet., 35(1–6) (1997) 125–132.
AMCTB No. 74, z-Scores and other scores in chemical proficiency testing - their meanings, and some common misconceptions, Analytical Methods, 8, (2016)
Analytical Methods Committee, Proficiency testing of analytical laboratories: organization and statistical assessment. Analyst, 117 (1992) 97–104.
Acknowledgements
The authors would like to express their appreciation to Dr. D. K. Aswal, Director HS&EG, BARC for his support. The authors also thank colleagues of EMAD and HPD for the support rendered during the study.
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Jha, S.K., Sartandel, S.J. The Use of Z-scores in External Performance Evaluation of Inter-comparison Exercises. MAPAN 39, 37–40 (2024). https://doi.org/10.1007/s12647-023-00701-6
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DOI: https://doi.org/10.1007/s12647-023-00701-6