TS ISO 3951-2

TS ISO 3951-2 defines the general rules for single sampling plans indexed by AQL for inspection by variables and addresses an acceptance sampling system for lot-by-lot inspection of independent quality characteristics. In practical terms, it supports a statistically based way of judging product conformity from measurement data rather than from simple conforming/nonconforming counts.

What inspection by variables means

Inspection by variables uses measured values to support an accept/reject decision. This is especially useful when quality characteristics are independent and can be assessed separately, because the average and spread of the measurements provide more information about the lot than attribute counting alone. The Acceptance Quality Limit, or AQL, is the indexing concept commonly used in acceptance sampling to relate a sampling plan to an accepted level of process quality over time.

What this part provides

• General rules for single sampling plans indexed by AQL.
• An acceptance sampling system for lot-by-lot inspection.
• A focus on independent quality characteristics, with each characteristic treated separately.
• A framework for acceptance decisions based on variables inspection principles.

In general technical use, standards like this help establish a consistent statistical basis between supplier and customer. They are especially relevant in repetitive production, where inspecting every unit is impractical and a limited number of measurements must support a decision; the value of that decision depends on selecting an appropriate sampling plan and on reliable measurement practice. TS ISO 3951-2 standardizes that acceptance-sampling language for inspection by variables.