TS ISO 3951-1

TS ISO 3951-1 is the standard for single sampling plans used in lot-by-lot inspection by variables, indexed by the acceptance quality limit (AQL). It addresses acceptance sampling for a single quality characteristic and places measurement data, rather than simple pass/fail counts, at the centre of the decision process. In practical terms, it belongs to the family of statistical quality control methods used when product quality is assessed from measured values.

What inspection by variables means in practice

Inspection by variables uses numerical measurements to judge conformity. Because it considers the distribution and spread of the data, it can provide a more informative basis for accept/reject decisions than attribute inspection alone. In general technical terms, this approach is especially useful when the characteristic being checked is continuous, such as a dimension, strength, mass, or other measurable property. The AQL is the indexing concept used to organise acceptance sampling plans by an acceptable process quality level.

How this part is positioned

This part focuses on single sampling plans and is intended for users with simple requirements or those who are familiarising themselves with sampling by variables. In broader quality assurance practice, such plans are used in incoming inspection, production control, and lot acceptance decisions for a single measurable characteristic. The standard specifies an acceptance sampling system; any detailed plan parameters, numerical limits, or procedural steps must be taken from the text of the standard itself.

• Covers a single quality characteristic.
• Applies to lot-by-lot inspection.
• Uses single sampling plans indexed by AQL.
• Belongs to acceptance sampling by variables.
• Designed for users with relatively simple requirements.