Multiple teams: the most effective way to drive consistent and effective sampling schemes is not writing a document for them to follow. A brief outline of the basic steps such as determine the defects (failures) and their severity on the patient/Customer, etc. is good practice. However the really effective action is to have the subject matter expert coach the teams. This way they learn and you get good results. Otherwise the teams only remember what to do and you have not improved the collective knowledge of your organization.
High confidence levels: this is something that regulatory reviewers often chase. The FDA is no different. Again the confidence levels are increasing beyond 95% as defects of any kind continue to become less and less tolerated. All of this leads to larger and larger sampling sizes. The only remedy here is to have open and honest communication with your reviewer and the stats group.
As stated before the only remedy to larger sample sizes is to have well characterized processes (KNOW how your inputs effect your outputs) and to implement effective process controls. Note that is plural. A single process control is not sufficient. A better approach to inspection than random sampling at the end is to perform targeted sampling of small sample sizes: when you understand how your processes vary, you can take small sample sizes at the change points to determine the state of the process. Well characterized and controlled processes rarely have random defects. these processes tend to produce systemic defects (not always but often) such that once a defect is produced, the process continues to produce defects until it is corrected. Also remember that SPC will detect shifts and trends before defects are created. For truly random defects - usually related to operator errors or inherent in-capability of processes (in other words not well characterized or controlled) is 1. Mistake proofing to prevent the error or catch the defect and 2. Fix the process. While all of this sounds like hard work it is not as hard or expensive as inspection with large sample sizes, remediation of defective lots and dealing with escapes to your Customers. In fact it is nothing but good engineering and science.
Will the FDA - or any regulatory agency - accept this instead of huge sample sizes? Sometimes. Sometimes they won’t immediately. They need proof and trust. You must invest in ongoing communication and partnership with them. You must characterize and control your processes. You must care about quality. Unfortunately many - not all - of these regulatory agencies are way behind the times when it comes to Quality. Their default ‘control’ is inspection. And that’s the fault of business. As long as we don’t characterize and control our processes, as long as we make short term ‘economic’ decisions about known quality defects these agencies will dig in to the only defense they have: oppressive inspections. It is easy for them to audit and maintain legal recourse in the event of an escape.
an follow through question is that, can mistake proofing and process controls set the argument for lower levels of probability!?
