The Health Care Data Guide: Learning from Data for Improvement

APPENDIX 5.1

CALCULATING SHEWHART LIMITS

I CHART

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:

6. ...