Some common examples of a possible root cause you may encounter are:
- Lack of or incomplete training
- Design of the process
- Change control/communication
- Inadequate standard operating procedures (SOPs)
- Purchasing/supplier quality issues
- Neglected quality control (QC) trends or outliers
- Lack of documentation
- Insufficient instrument maintenance
Try not to overuse "training" as a root cause, as this may not adequately address the systematic process failures.