1 Scope
This Part of GB/T 2828 establishes sampling plans and procedures that can be used to assess whether the quality level of an entity (lot, process, etc.) conforms to a declared quality level. The sampling plans have been devised so as to obtain a risk of less than 5% of contradicting a correct entity (lot). The risk is 10% of failing to contradict an incorrect entity (lot) whose actual quality level is LQR times of declared quality level (see Chapter 4). Sampling plans are provided corresponding to four levels of discriminatory ability.
In contrast to the procedures in the other Parts of GB/T 2828, the procedures in this Part are not applicable to acceptance assessment of lots. This Part of GB/T 2828 may be used for various forms of quality inspection in situations including the situation where the inspection results of samples are used to state whether a certain audit population conforms to a certain declared quality level.
This Part of GB/T 2828 is applicable to entities such as lots, process output, etc. that allow random samples of individual items to be taken from the entity.
The sampling plans provided in this Part of GB/T 2828 are applicable, but not limited, to inspection of a variety of products such as:
--End items;
--Spare parts and raw materials;
--Operations;
--Materials in process;
--Supplies in storage;
--Maintenance operations;
--Data or records;
--Administrative procedures.
The procedures are primarily intended to be used when the quantity of interest is the number or fraction of nonconforming items for which the inspected items are classified as conforming or nonconforming.
With minor changes, the procedures may also be used when the quantity of interest is the number of nonconformities or number of nonconformities per 100 items. The necessary changes are:
--Replacement of “number of nonconforming items” by “number of nonconformities”;
--Replacement of “percent nonconforming items (or number of nonconforming items per 100 items)” by “nonconformities per 100 items".
In this case the values given in Tables 2 to 9 are only approximations
The values given in Tables 2 to 9 are calculated by binomial distribution method. Sampling plans indexed from this Part are approximations where the audit population quantity is less than 250, or the ratio of audit population quantity to sample size is greater than 10.Sampling plans may be determined according to the methods specified in GB / T 15482.
Contents
Foreword i
Introduction iii
1 Scope
2 Normative References
3 Terms, Definitions and Symbols
3.1 Terms and Definitions
3.2 Symbols and Abbreviations
4 Principles
5 Declared Quality Level (DQL)
6 Sampling Plans
6.1 LQR (Limiting Quality Ratio) Level
6.2 Selection of a Sampling Plan
7 Sampling Inspection Procedures Implementation
7.1 Audit Population Determination
7.2 Technical Performance, Quality Characteristic and Requirements Determination for Unit Product
7.3 Nonconforming Item Classification Determination
7.4 Declared Quality Level Specification
7.5 LQR Level Specification
7.6 Sampling Plan Index
7.7 Sample Selection
7.8 Sample Inspection
7.9 Disposition of Nonconforming Items
7.10 Judgment Criteria
7.11 Repeat Test or Inspection
8 Further Information
8.1 Curves Showing Approximate Probability of Contradiction
8.2 Tables Indicating Discriminatory Ability
Appendix A (Normative) Situation for Declared Quality Level DQL Equal to
Appendix B (Informative) Examples of Use of the Procedures
Appendix C (Informative) Revision Explanation for ISO 2859-4:
Bibliography
