Term | Description |
---|---|

USL | Upper specification limit |

LSL | Lower specification limit |

Toler | Multiplier of the sigma tolerance (Minitab uses 6 as the default value) |

Between/within standard deviation |

The expected number of parts per million that are outside of the specification limits, based on the variation between/within subgroups, is

Term | Description |
---|---|

PPM | Parts per million |

LSL | Lower specification limit |

USL | Upper specification limit |

Φ (X) | Cumulative distribution function (CDF) of a standard normal distribution |

x̅ | Average of the observations |

Between/within subgroup standard deviation |

Benchmark Z statistics for between/within capability are calculated by finding the Z value using the standard normal (0,1) distribution for the corresponding statistics.

where:

Term | Description |
---|---|

LSL | Lower specification limit |

USL | Upper specification limit |

Φ (X) | Cumulative distribution function (CDF) of a standard normal distribution |

Φ^{-1} (X) | Inverse CDF of a standard normal distribution |

Between/within standard deviation |