m Chart Template in Excel
The Purpose of a m Chart is to Evaluate Process Stability When You Have Summarized Median and Standard Deviation Data
The m chart is used when the sample size varies: e.g., the total number of cases in a hospital varies from one period to the next.
Here is a sample of a m chart created using QI Macros SPC Software for Excel. The stair step or skyline control limits are the result of the varying sample sizes.
m chart data looks like this: