Available QCC Types

Even though the configuration parameters of the different QCC types are the same, each QCC has a different purpose. The different QCCs are briefly explained here. A description of when which exact type of QCC could be used, as well as its formulas, is not part of this topic. Which QCC to use and when to use it is covered in the SPC training courses.

The following QCCs are available:

• Analysis QCC - Ensures process assessment (Process Analysis)
• SPC QCC - Provides the basis for statistical process control (Process Analysis)
• Saved QCC - "Deployed" QCC for statistical process control (O-QIS)
• Online QCC - "Notification" QCC for alarm/e-mail/test plan lock (O-QIS)

Analysis QCC

The Analysis QCC has an exclusive meaning within the Process Analysis module. It is designed to asses whether the measurement process is stable or unstable. In the classic sense, it is a loop that surrounds the process. The Analysis QCC has only an "observational" character.

The calculation is carried out according to the path of the evaluation strategy using the settings in the "Analysis" line.


The Analysis QCC is recalculated each time a data set is opened or the evaluation is executed.

Previous ISO standards required evaluation strategies to precisely define "stable" and  "unstable" requirements. As an example here the "Q-DAS 1 - Part" evaluation strategy.

Depending on this, the appropriate requirements tabs are accessed, for other C-values as well as C-value identifiers, or other calculation formulas.

Newer evaluation strategies such as the "Q-DAS Process Capability (01/2020)" follow the newer ISO standards where the requirements are no longer relevant for Analysis QCCs. The paths of the distribution time models define which path is considered stable and which path is considered unstable. The paths of distribution time models A (left marking) are considered stable, all other distribution time models are considered unstable (right marking).

In the case of using the paths of the distribution time models, the Analysis QCC is no longer dependent on the results of the requirements. 

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SPC QCC

The SPC QCC only has a significance in Process Analysis module. While the Analysis QCC is designed to assess the stability of the measurement process, the purpose of the SPC QCC is to provide the user with a suggestion for a QCC, which can then be stored for use in statistical process control.

Therefore, the SPC QCC is often configured so the "Estimator of the Target" is the center of the tolerance. An example shows the Analysis QCC on the left and the SPC QCC on the right.

The SPC QCC is the template QCC. It is used to create the QCC that will be saved when requested by the user. In other words: It is a template for the Saved QCC.

The calculation is carried out according to the path of the evaluation strategy using the settings of the "O-QIS" line.

The SPC QCC is recalculated each time a data set is loaded or the evaluation is executed.

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Saved QCC

When a QCC is saved, the content from the SPC QCC is copied into the corresponding K-fields of the dataset. The Saved QCC is, so to speak, a copy of the SPC QCC at time the data set was last saved. While the SPC QCC is being recalculated, the Saved QCCs are used to display the "recent used" QCC contents stored in the dataset.

The Saved QCC always shows content. Even if there is no saved QCC. The raw values are shown as subgroups if there is no Saved QCC for a characteristic (left). If a characteristic has a Saved QCC, the QCC information, e.g. QCC limits, are displayed in addition to the subgroups (right).

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Online QCC

The Online QCC is only available in the O-QIS modules. It is used for follow-up escalations such as alarm/email/test plan lock.
The "source" of the Online QCC is determined by the evaluation strategy.

A brief description of the options available

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QCC for discrete characteristics

In the case of attributive characteristics, there is only one setting that applies equally to Analysis QCC and SPC QCC. This can be found in the evaluation strategy under "Requirement of attribute characteristics".


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