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Critical values of Mandel’s h and k, the Grubbs and the Cochran test statistic

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According to ISO 5725-2 (1994), measurement results obtained in an interlaboratory experiment are inspected for consistency by plotting Mandel’s h and k statistics and for outliers by application of the Grubbs test and the Cochran test. Critical values of these statistics for significance levels α=5% and α=1% and for some numbers p of laboratories and n of repeated measurements in the laboratories are supplied in ISO 5725-2 without reference to methods for their calculation. In this paper, exact formulae for the critical values of Mandel’s h and k and approximate formulae for the critical values of the Single Grubbs test, the Double Grubbs test and the Cochran test are derived.

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Correspondence to Peter-T. Wilrich.

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Wilrich, P. Critical values of Mandel’s h and k, the Grubbs and the Cochran test statistic. AStA Adv Stat Anal 97, 1–10 (2013). https://doi.org/10.1007/s10182-011-0185-y

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  • Cochran test
  • Grubbs test
  • Mandel’s h and k statistics
  • Outlier tests