Cheat Sheet (Extra Module)

Cheat Sheet (Extra Module)#

I-MR Chart#

  • X-chart (n=1)

    • UCL \(= \bar{x} + \frac{3}{\sqrt{n}} \frac{\bar{MR}}{d_2} = \bar{x} + 3 \frac{\bar{MR}}{1.128}\)

    • CL \(= \bar{x}\)

    • LCL \(= \bar{x} - 3 \frac{\bar{MR}}{1.128}\)

  • MR-chart (must consider n=2 since variance cannot be estimated for a single value)

    • UCL \(= D_4 \bar{MR} = 3.267\bar{MR}\)

    • CL \(= \bar{MR}\)

    • LCL \(= D_3 \bar{MR} = 0\)

Variable Subgroup Sizes#

  • p-chart or u-chart can have variable “sub-group” sizes.

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