Statistical Acceptance Sampling Protocols for Paperboard Package Lot Verification
Statistical lot verification protects packaging buyers by tying standardized sample testing directly to batch acceptance quality limits and contract settlement terms.
Double Sampling Plan
Statistical Procedure
Quality assurance protocols evaluate lot compliance through a two-stage inspection process before reaching a final acceptance decision. Technical inspectors execute a double sampling plan by extracting an initial sample from a paper reel or carton lot and counting non-conforming units against low and high threshold limits. Immediate acceptance occurs if defect counts remain below the lower boundary, whereas immediate rejection occurs if counts exceed the upper boundary.
Intermediate defect counts trigger a second sample draw to reach a conclusive result.
Decision Logic
Sampling tables defined in standards like ISO 2859-1 dictate exact sample sizes and acceptance numbers for each evaluation phase. An auditor inspecting a batch of folded cartons evaluates the initial sample and tallies defects against the primary acceptance number. When defect levels fall into the indecisive range, the auditor inspects a second sample of specified size and adds those defects to the original tally.
Final lot approval requires the combined defect count to remain at or below the cumulative acceptance number.
Sample Economy
Total inspection effort decreases across clean or severely defective production runs compared to single sampling approaches. High-quality paper production lots pass after the first smaller sample group, which reduces laboratory testing hours and destructive burst tests. Average sample numbers drop across historical quality data while maintaining statistical confidence limits.