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Publication date: 11/10/2021

Work with Control Limits

Control limits are based on the performance of your process and tell you about the variability in your process. Upper control limits (UCLs), center lines, and lower control limits (LCLs) are calculated from the data when a control chart is created. You can use these calculated control limits to indicate when your process has changed.

It is important to note that control limits are different from specification limits, which are often used in capability analysis.

Table 3.9 Control Limits versus Specification Limits

Control Limits

Specification Limits

Calculated from data

Defined by the customer or design

Based on variability

Based on system requirements

The voice of the process

The voice of the customer

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