Skipping inspection of some lots requires a defined qualification history and return rule. A reduced fraction alone does not identify a complete scheme.
The statistical question
Skip-lot sampling inspects a fraction of submitted lots after a specified qualification sequence under a reference plan. In the NIST description, selected lots are chosen randomly, and a rejected inspected lot returns the scheme to normal inspection. The clearance requirement, inspection fraction and reference plan identify the arrangement; unsupported confidence in a supplier does not replace them.
An illustrative review example
For a fictional planning discussion, a team proposes an inspection fraction of 0.25 after its agreed qualification requirements are met. That fraction concerns which lots are selected, not inspecting one quarter of every selected lot. The selected lot still uses its reference sampling plan. Nor does the fraction guarantee exactly five inspected lots in every block of 20 when selection is random. The actual lot-selection record is needed.
Prepare the evidence for discussion
Ask the responsible quality owner to identify eligibility evidence, the qualification counter, random selection records and the event that reinstates normal inspection. Keep any change in product, supplier or lot definition visible for their review. This guide supplies no release authorization or regulatory scheme. Use the approved arrangement to estimate incoming-component workload, then retain the complete inspection history supporting its continuing applicability.
Qualified lots and a return rule
This blank worksheet is for your own project. It contains no H M machine trial result.
| Question to resolve | Evidence to retain |
|---|---|
| Eligibility | Documented qualification history |
| Selected lot | Random selection evidence |
| Reference plan | Inspection within selected lots |
| Return event | Normal-inspection trigger |
Customer Questions
Does the inspection fraction reduce every sample?
It concerns the fraction of lots selected; the reference plan governs inspection of a selected lot.
Is a good supplier reputation enough?
The scheme requires its defined qualification evidence and applicable return-to-inspection rule.
Does random selection guarantee a fixed count per short block?
No. A selection probability does not prescribe an exact count in each short block.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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