QI Macros Control Chart Menu

Remove Point from Control Chart Calculations
(Ghost Point)

While it is not usually recommended, many customers have asked for the ability to leave a point on a control chart BUT remove the point from the control limit calculations. Using the chart pull down menu, QI Macros now give you this capability.

To remove a point from the calculations but leave it on a chart:

  1. Click on the point to be removed. Note: The first time you click on the point, Excel will select the whole line. Click on the point a second time to get just the point. If you have done this correctly, Excel will highlight your point and the point before it.
    select point on control chart
  2. Select the QI Macros Chart menu and select Ghost Point.

    remove a point from control limit calculations but leave on chart
  3. The point marker will change to designate that the point has been "ghosted."point marker changes for a ghosted point on a control chart
  4. Next re-run stability analysis with the new control limits.
  5. If you want to check the control limit calculations, go to the data sheet where the formulas are created and click on one of the average cells. Look in the formula box to view the formula. You will notice that the row that the ghosted point is in has been removed from the calculations. In the example below, the point in row 19 has been removed.control chart calculations with ghosted point removed
  6. You may also want to add text to the point to further highlight that it has been removed from the calculations.

Excel 2007 Workaround for Ghosting a Point on an Embedded Chart

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