Cochran’s statistic C: |
where s_{max} is the largest standard deviation amongst the s_{i}. |

Mandel’s k-statistic | Plot values for k_{ij} in the order of measurements made (by laboratory, e.g) and grouped by level. Draw in limits for 1% resp 5%. |

Range- (R-)diagram |
Plot values of the sample range, R (= x_{max} – x_{min}), against time. Action limits lie at k_{3}s_{r}. Warning limits lie at + k_{2}s_{r} |

F-test | for the new (n) resp. old (o) measurements.Compare F with F_{max} for a certain number of number of degrees of freedom (= j + k – 2) and confidence level, which can be obtained from a table of overprocent points for the F-distribution (95%) resp. (99%). |

Process capability | where UTL resp. LTL are the upper and lower tolerance limits, and PS is the process scatter, s._{p} |

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