Outliers in Interlaboratory Testing

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Volume 21, Issue 2 (March 1993)

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ISSN: 0090-3973
Page Count: 4

Outliers in Interlaboratory Testing
Mandel, J
National Institute of Standards and Technology, Chemical Science and Technology Laboratory, MD

(Received 6 June 1992; accepted 9 September 1992)

Abstract

The widespread practice of rejecting outliers on the basis of statistical tests of significance is shown to accomplish nothing in terms of finding the causes for discrepancies. A graphical procedure, based on the h-statistic and the k-statistic, is shown to provide a vivid picture of the biases and the internal precisions of the participating laboratories. It is highly recommended that the analysis of the data be followed by an investigation of causes of outhers and thereby lead to improvements in repeatability and reproducibility.

Keywords:
interlaboratory testing, outliers, rejection, repeatability, reproducibility

Paper ID: JTE11757J
DOI: 10.1520/JTE11757J
ASTM International is a member of CrossRef.

Author Title Outliers in Interlaboratory Testing Symposium , 0000-00-00 Committee E36

		Home Journals STPs Manuals Topics Subscriptions/Pricing Digital Library / Journals / Journal of Testing and Evaluation (JTE) / Citation Page Volume 21, Issue 2 (March 1993) Click here to download this paper now for $25 PDF (352K) View License Agreement ISSN: 0090-3973 Page Count: 4 Outliers in Interlaboratory Testing Mandel, J National Institute of Standards and Technology, Chemical Science and Technology Laboratory, MD (Received 6 June 1992; accepted 9 September 1992) Abstract The widespread practice of rejecting outliers on the basis of statistical tests of significance is shown to accomplish nothing in terms of finding the causes for discrepancies. A graphical procedure, based on the h-statistic and the k-statistic, is shown to provide a vivid picture of the biases and the internal precisions of the participating laboratories. It is highly recommended that the analysis of the data be followed by an investigation of causes of outhers and thereby lead to improvements in repeatability and reproducibility. Keywords: interlaboratory testing, outliers, rejection, repeatability, reproducibility Paper ID: JTE11757J DOI: 10.1520/JTE11757J ASTM International is a member of CrossRef. Author Title Outliers in Interlaboratory Testing Symposium , 0000-00-00 Committee E36