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.
The following standards contain provisions which, through reference in this text, constitute provisions of this Part of GB/T 2828. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards. For undated references, the latest edition of the normative document referred to applies.
GB/T 321 Preferred numbers -Series of preferred numbers
GB/T 2828.1-2003Sampling procedures for inspection by attributea-Part1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection (ISO 2859-1: 1999, IDT)
GB/T 2828.2-2008 Sampling procedures for inspection by attributes - Part 2: Sampling plans indexed by limiting quality (LQ) for isolated lot inspection (ISO 2859-2: 1985, NEQ)
GB/T 2828.3-2008 Sampling procedures for inspection by attributes - Part 3: Skip-lot sampling procedures (ISO 2859-3: 2005, IDT)
GB/T 15482 Single sampling procedures and tables for product quality audit of small population by attributes
GB/T 16306 Re-inspection and re-test procedures for assessment of declared quality levels
GB/T 19000-2000 Quality management systems-Fundamentals and vocabulary (ISO 9000: 2000, IDT)
ISO 3534-1: 2005 Statistics -- Vocabulary and symbols -- Part 1: General statistical terms and terms used in probability
ISO 3534-2: 2006 Statistics -- Vocabulary and symbols -- Part 2: Applied statistics
Contents
Foreword i
Introduction iii
1 Scope 1
2 Normative References 2
3 Terms, Definitions and Symbols 2
3.1 Terms and Definitions 2
3.2 Symbols and Abbreviations 4
4 Principles 4
5 Declared Quality Level (DQL) 6
6 Sampling Plans 6
6.1 LQR (Limiting Quality Ratio) Level 6
6.2 Selection of a Sampling Plan 9
7 Sampling Inspection Procedures Implementation 9
7.1 Audit Population Determination 9
7.2 Technical Performance, Quality Characteristic and Requirements Determination for Unit Product 9
7.3 Nonconforming Item Classification Determination 10
7.4 Declared Quality Level Specification 10
7.5 LQR Level Specification 10
7.6 Sampling Plan Index 10
7.7 Sample Selection 10
7.8 Sample Inspection 11
7.9 Disposition of Nonconforming Items 11
7.10 Judgment Criteria 11
7.11 Repeat Test or Inspection 12
8 Further Information 12
8.1 Curves Showing Approximate Probability of Contradiction 12
8.2 Tables Indicating Discriminatory Ability 13
Appendix A (Normative) Situation for Declared Quality Level DQL Equal to 0 17
Appendix B (Informative) Examples of Use of the Procedures 18
Appendix C (Informative) Revision Explanation for ISO 2859-4: 2002 21
Bibliography 22
