CALCULATING SHEWHART LIMITS
The steps for developing a Shewhart chart for individuals are the following:
1. Calculate the k−1 moving ranges and the average of the moving ranges (MRbar)
2. Calculate the upper limit for the moving range using:
3. Remove any moving range bigger than the ULMR and recalculate the average moving range (MRbar).
(Note: This recalculation should be done only once.)
4. Calculate the average of the k measurements (Ibar) for the center line (CL).
5. Calculate the limits for the I chart using: