Double Sampling Plan

Second Stage

Efficiency improves when the first sample is small enough to clear very high-quality batches quickly. The double sampling plan only moves to the second round when the first set of data is inconclusive. This approach lowers the average number of units inspected compared to standard single-stage checks.

Rejection Logic

Combined data sets decide the final fate of the batch after the second round. If the total count of defects from both rounds exceeds the cumulative threshold, the lot is rejected. Logistics teams prefer this method when inspection resources are limited but accuracy is required for borderline cases.

It balances the need for speed with the requirement for statistical certainty in trade.

Inspection Load

Sampling volumes vary depending on the initial results. A double sampling plan requires strict bookkeeping to ensure the two samples are not mixed before the final count.