TS ISO 3951-2/A1

TS ISO 3951-2/A1 is an amendment to ISO 3951-2, the standard that sets out the general specification for single sampling plans indexed by acceptance quality limit (AQL) for lot-by-lot inspection by variables. Its subject is acceptance sampling based on measured data rather than simple pass/fail counts, applied to independent quality characteristics.

In practical terms, this area deals with how measurements taken from a sample are interpreted to make a decision about an entire lot when each quality characteristic is assessed separately. AQL-based indexing is a well-established sampling concept that links long-run process quality with acceptance decisions. This record, however, represents the amendment document itself, not the full base standard on its own.

Measured characteristics and the meaning of independence

Measured characteristics are continuous quality variables such as dimensions, mass, resistance, or strength. Independent quality characteristics means that the decision for one characteristic is not directly tied to the result of another, so each characteristic is evaluated as a separate statistical case. This distinction is central to understanding variable inspection versus attribute inspection.

Why AQL-indexed acceptance sampling matters

In general technical use, acceptance quality limit is a reference value used when selecting sampling plans and relating them to an acceptable quality level. Such plans make it possible to decide on large lots from a limited number of measurements instead of inspecting every item individually. As an amendment, this document updates and supplements the parent standard’s framework; it does not, by itself, define a standalone full methodology beyond that revised context.