Best Practices in Statistical Process Monitoring ... - IBC Life Sciences

6. How to Handle Unusual Data
Situation
“out of control”
historical data
“non-normal”
historical data
LoQ assays
(e.g. LaL, purity)
Strategies/Comments
• Exclude special cause variability
• Incorporate all common cause variability
• Short horizon reference range often too narrow
• Utilize moving range for control limit calculations.
• 3 limits often apply 1
• Avoid complex WE/Nelson rules
• Transform data prior to applying rules
• Visually inspect trends instead
• If sufficient data is available >LoQ, exclude