Select the method or formula of your choice.

Minitab uses an algorithm to solve the following equations for n, sample size, and c, acceptance number.

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

α | producer's risk |

β | consumer's risk |

p_{1} | acceptable quality level (AQL) |

p_{2} | rejectable quality level (RQL) or lot tolerance percent defective (LTPD) |

0 < p_{1}< p_{2}< 1

1 > 1-α > β > 0

The probability of acceptance (P_{a}) describes the chance of accepting a particular lot based on a specific sampling plan and incoming proportion defective. It is based on the binomial distribution.

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

c | acceptance number |

n | sample size |

p | fraction defective |

The probability of rejecting (P_{r}) describes the chance of rejecting a particular lot based on a specific sampling plan and incoming proportion defective. It is simply 1 minus the probability of acceptance.

P_{r} = 1 – P_{a}

where:

P_{a} = probability of acceptance

The average outgoing quality represents the quality level of the product after inspection. The average outgoing quality varies as the incoming fraction defective varies.

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

P_{a} | probability of acceptance |

p | incoming fraction defective |

N | lot size |

n | sample size |

The average total inspection represents the average number of units that will be inspected for a particular incoming quality level and probability of acceptance.

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

P_{a} | probability of acceptance |

N | lot size |

n | sample size |