New member to this forum. I'm trying to understand the formula to calculate the UNSHIFTED PPM level. I've found various tables that give the UNSHIFTED PPM levels, such as the table below. But I'm unable to find the formula to give these results. When I use the normal functions in Excel (i.e. NORMSDIST, NORMSINV), it's giving me PPM levels that are exactly 1/2 of the values in the table below. For example:

- At Sigma Level = 3, the Excel formula gives me PPM level 1,350, but the table below gives me 2,699.
- At Sigma Level = 4, the Excel formula gives me PPM Level 32, but the table below gives me 63.
- .... using Excel formula always gives PPM Levels which are exactly 1/2 of the values in the table below.

1.5 Shift | Unshifted | |

Sigma | PPM | PPM |

1 | 691,462 | 317,300 |

2 | 308,538 | 45,500 |

3 | 66,807 | 2,699 |

4 | 6,210 | 63 |

5 | 233 | 1 |

6 | 3 | 0 |