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We inspect product after sterilization based upon the Z-1.4 standards. For this particular product line, the inspection is Level S3, AQL 1.0% (lot sizes are typically 500 – 1000). This results in 13 samples being randomly inspected (Accept on 0 Rejects, Reject on 1 Reject). We had 1 failure out of the 13 samples inspected (7.69%). The investigation determined that it was most likely an isolated incident. To prove out this point, the remaining 16 samples from the batch (a subset of the lot) were pulled and then an additional random 13 samples were pulled from the remainder of the lot.
I am trying to provide my confidence that the issue is isolated. Can I say that based upon the 29 acceptable samples pulled after the investigation that we are 90.2% confident that the lot is not 7.69% defective (1 out of 13 failures) or do I need to say that we are 84.4% confident that the lot is not 7.69% defective (42 total samples, 1 reject). Note: These values come from Minitab.
If none of these statements are true, what would be a good way to explain my confidence in the acceptability of the lot?
I am trying to provide my confidence that the issue is isolated. Can I say that based upon the 29 acceptable samples pulled after the investigation that we are 90.2% confident that the lot is not 7.69% defective (1 out of 13 failures) or do I need to say that we are 84.4% confident that the lot is not 7.69% defective (42 total samples, 1 reject). Note: These values come from Minitab.
If none of these statements are true, what would be a good way to explain my confidence in the acceptability of the lot?