Define the Data Points Used to Calculate Control Chart Limits

It's Easy to Set or Fix Limits in QI Macros Control Charts

When you create a control chart using QI Macros, the data you select is the baseline data. It is used to calculate the control limits. If you selected 20 points, 20 points are used. If you selected 14 points, then 14 points are used and so on. When you add data to an existing chart, the limits stay the same.

If you want to change the data points used to calculate the control limits after you have added new data:

use Recalculate UCL /LCL to use ALL of the data points.
use Fix Control Limits to use a subset of the data points.

Here's how to use the Fix Control Limits option:

Click on the point just to the right of the points you want to include in the fixed control limit calculations:
Click on the QI Macros Chart menu > Process Changes, and then select "Fix Control Limits":
QI Macros will use the points to the left of the selected point to calculate the fixed control limits:
Your chart will now indicate where the Fixed Control Limits point is, as the centerline to the left of the point will be dashed, while the centerline to the right of your point is solid:
Don't forget to click on Analyze Stability to rerun stability analysis using the new control limits: