Select the method or formula of your choice.

Each data point, MR* _{i} *, is the moving range of the x values in each group. MR

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

MR | moving range |

w | Number of observations in the moving range. By default, w = 2. |

The center line is the unbiased estimate of the average of the moving range.

center line = MR * d_{2}(w)

- MR
- the estimate of the average moving range for the method that you use to estimate the standard deviation
- d
_{2}(w) - the unbiasing constant given in this table
- w
- the number of observations that are used in the moving range

The LCL is the greater of the following:

or

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

d_{2}() | a constant used to estimate the standard deviation |

w | number of observations in the moving range. By default, w = 2. |

σ | process standard deviation |

k | parameter for Test 1 (default is 3) |

d_{3}() | A constant used to estimate LCL and UCL. |