CUSUM Example: Calculating CUSUM
- Now, we'll calculate the CUSUM value for each daily control.
- The CUSUM tracks the cumulative distance from the mean, taking into account whether each daily control fell above or below the mean.
- On March 2, the daily result equaled the control, so the CUSUM is 0.
- On March 3, the daily control was +3 from the mean, so we add +3 to the previous day's CUSUM, for a total of +3.
- On March 4, the daily control was -1 from the mean, so we add -1 to +3, resulting in +2.
- On March 5 and 6, the CUSUM again changes -1 each day, since each control result is -1 from the mean.