Quality and Process Methods • Shewhart Control Charts • Excluded, Hidden, and Deleted Samples
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Excluded, Hidden, and Deleted Samples
The following table summarizes the effects of various conditions on samples and subgroups:
Table 3.2 Excluded, Hidden, and Deleted Samples 
All rows of the sample are excluded before creating the chart.
Sample is not included in the calculation of the limits, but it appears on the graph.
Sample is excluded after creating the chart.
Sample is included in the calculation of the limits, and it appears in the graph. Nothing changes on the output by excluding a sample with the graph open.
Sample is hidden before creating the chart.
Sample is included in the calculation of the limits, but does not appear on the graph.
Sample is hidden after creating the chart.
Sample is included in the calculation of the limits, but does not appear on the graph. The sample marker disappears from the graph, the sample label still appears on the axis, but limits remain the same.
All rows of the sample are both excluded and hidden before creating the chart.
Sample is not included in the calculation of the limits, and it does not appear on the graph.
All rows of the sample are both excluded and hidden after creating the chart.
Sample is included in the calculation of the limits, but does not appear on the graph. The sample marker disappears from the graph, the sample label still appears on the axis, but limits remain the same.
Data set is subsetted with Sample deleted before creating chart.
Sample is not included in the calculation of the limits, the axis does not include a value for the sample, and the sample marker does not appear on the graph.
Data set is subsetted with Sample deleted after creating chart.
Sample is not included in the calculation of the limits, and does not appear on the graph. The sample marker disappears from the graph, the sample label is removed from the axis, the graph shifts, and the limits change.
Some additional notes:
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Hide and Exclude operate only on the row state of the first observation in the sample. For example, if the second observation in the sample is hidden, while the first observation is not hidden, the sample will still appear on the chart.
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An exception to the exclude/hide rule: Both hidden and excluded rows are included in the count of points for Tests for Special Causes. An excluded row can be labeled with a special cause flag. A hidden point cannot be labeled. If the flag for a Tests for Special Causes is on a hidden point, it will not appear in the chart.
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Because of the specific rules in place (see Table 3.2), the control charts do not support the Automatic Recalc script.

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Help created on 10/11/2018