Example for common cause variation in Stastical process control

Here are some real-world examples of common cause variation in Statistical Process Control (SPC):

- Minor fluctuations in raw material properties, such as the thickness or density of a material, leading to small variations in the final product dimensions[1][2][3]

- Slight changes in environmental conditions like temperature or humidity from day to day, causing small shifts in a chemical process's yield[1][3]

- Natural variation in operator technique or skill level, resulting in small differences in product quality characteristics between individual workers[1][3]

- Random variation in machine performance over time due to normal wear and tear, leading to gradual changes in a process output[1][2][3]

- Minor differences in measurement instruments or calibration, contributing to small variations in data collected during the process[1][3]

Common cause variation is the inherent, random variability that is always present in a stable process. It represents the normal "noise" of the system and cannot be traced back to a specific, assignable source. As long as this variation remains within the control limits on a control chart, it indicates the process is in a state of statistical control.[1][2][3]

Citations:

[1] Achieving Process Stability with Common Cause Variation - iSixSigma https://www.isixsigma.com/dictionary/common-cause-variation/

[2] How to Identify Causes of Variation in Statistical Process Control https://safetychain.com/blog/identifying-variation-statistical-process-control

[3] What is Common Cause Variation in Six Sigma? - SixSigma.us https://www.6sigma.us/cause-variation/what-is-common-cause-variation/

[4] Common and Special Causes in Statistical Process Control - LinkedIn https://www.linkedin.com/advice/0/what-some-common-tools-techniques-identifying

[5] Common Cause and Special Cause - MSI Six Sigma Training https://www.msicertified.com/common-cause-and-special-cause/