NBN ISO 28596:2023

This document specifies two-stage (double) sampling plans by attributes for inspection for a proportion of nonconforming items in a target population of discrete units, in particular:

a) the proportion of nonconforming items in a lot of product items;

b) the proportion of nonconforming function instances of an internal control system (ICS);

c) the proportion of misstatements in a population of accounting entries or booking records;

d) the proportion of nonconforming test characteristics of an entity subject to an acceptance test, e.g. in product and process audits.

The plans are preferable to single sampling plans where the cost of inspection is high or where the delay and uncertainty caused by the possible requirement for second samples is inconsequential. The statistical theory underlying the plans, tables and figures are provided in Annexes A through K.