GB/T 16307-2026Sequential sampling plans for inspection by variables for percent nonconforming (known standard deviation) (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

Drafting.

This document replaces GB/T 16307-1996 "Measurement Procedures and Sampling Tables for Truncated Sequential Sampling Inspection (Applicable to Cases Where Standard Deviation is Known)".

Compared with GB/T 16307-1996, the main technical changes in the revised standard (including structural adjustments and editorial modifications) are as follows.

---The scope of this document has been changed; the phrase "the sampling plan is indexed by producer risk quality and user risk quality" has been modified.

The definition that "sampling plans are indexed by producer risk points and user risk points" expands the scope of application, making these plans not only applicable to...

It is applicable to acceptance sampling, and also to the testing of more general simple proportional statistics hypotheses (see Chapter 1, 1.1 of the 1996 edition);

---Added a sampling plan that satisfies the condition that "measurement error is negligible relative to the standard deviation of the production process" (see Chapter 1);

---Added a note stating "The sampling inspection procedures in this document are not applicable to batches where nonconforming items have been pre-screened" (see [link]).

Chapter 1);

---Change "Comprehensive bilateral regulatory limits" to "Joint control" and "Separate bilateral regulatory limits" to "Separate control" (see Chapter 3).

(Versions 3.1.14 and 3.1.15 from the 1996 edition)

---The note regarding the applicability of sequential schemes for testing the relationship between batch size and truncated sample size has been deleted (see 1.1 in the 1996 edition);

---The terms "unit product", "sample unit", "quality characteristics", "measuring quality characteristics", "measuring sampling inspection", and "sequential sampling inspection" have been removed.

"Verification", "Single-sided specification limit", "Two-sided specification limit" (see 1.1 of the 1996 edition);

--- Added terms such as "sampling inspection", "acceptance sampling", "acceptance sampling inspection", "metrological acceptance sampling inspection", "quality level", and "non-conforming".

"Unit", "Measurement", "User Risk and Quality", "Producer Risk and Quality", "Sequential Acceptance Sampling Inspection", "Sequential Sampling Plan", "Operation" "Characteristic curves", "Producer risk points", and "User risk points" (see Chapter 3);

---The principles of sequential sampling inspection schemes for measurement have been added (see Chapter 5);

---The sequential sampling procedure has been removed (see Chapter 5 of the 1996 edition);

---Changed the selection options for sampling plans, adding "Choice between measurement and counting" and "Choice between sequential sampling plan and single sampling plan".

The "choice" was changed to "producer risk points and user risk points", "QPR and QCR priority values", and "preparatory operations" (see section 6).

Chapter 4 (1996 edition);

---Added content on "Choosing Between Numerical and Graphical Methods" (see 7.4);

---The values of parameters hA, hR, and g were changed and recalculated to provide a solution that fully meets the requirements (see Chapter 9).

Table 1 (1996 edition).

This document adopts ISO 39511:2018 "Measurement – Truncation-tailed sequential sampling inspection procedures and sampling tables (for applications with known standard deviations)".

situation)".

The following minimal editorial changes have been made to this document.

---The upper limit of acceptance for a cumulative sample size of 3 (170.7) in Table 3 is modified to 170.8, and the lower limit for a cumulative sample size of 4 is modified accordingly.

The lower bound acceptance value of 111.6 has been revised to 111.5, and the lower bound acceptance value of 150.5 for a cumulative sample size of 6 has been revised to 150.4.

The lower limit of acceptance when the cumulative sample size is 8, which was 189.4, has been revised to 189.3.The original text was printed incorrectly.

Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed and is under the jurisdiction of the National Technical Committee on Standardization of Statistical Methods Application (SAC/TC21).

Introduction

In modern production processes, companies often expect their products to have a defect rate of one in a million, representing a high-quality level. In this situation...

Under these circumstances, using conventional acceptance sampling schemes (such as those provided in GB/T 2828.1) often requires extremely large sample sizes. If...

Using a metrological acceptance sampling plan (such as the one provided by ISO 3951-1), the sample size can be significantly reduced. However, especially in...

Even with extremely high requirements for the quality of the received products, the required sample size is still very large. Therefore, it is necessary to adopt a standard with the smallest possible sample size.

Sequential sampling is the only statistical sampling method that satisfies this need. This is because, among samples with similar statistical properties...

Among the possible sampling schemes, the sequential sampling scheme requires the smallest average sample size.

The main advantage of sequential sampling is that it reduces the average sample size. The average sample size is the minimum acceptable size for a given batch or process quality level.

The average of all possible sample sizes in a sampling plan. Compared to a single-sample plan with the same operational characteristics, sequential sampling...

The average sample size for the cases is smaller.

Other factors to consider include.

a) Complexity

Compared to the simple rules of a single sampling scheme, the rules of a sequential sampling scheme are slightly more complex.

b) Variability of the test quantity for a specific batch, the implementation of a sequential sampling plan can be challenging because the actual number of units to be inspected is unknown in advance.

For example, the arrangement of inspection procedures, etc.

c) Cost of sampling products If the cost of sampling products at different times is high, then the benefit of a reduced average sample size from a sequential sampling scheme may be negated.

The increase in sample costs was offset.

d) Duration of the test If the testing time for a single product is long, and multiple products can be tested simultaneously, then the testing time using a sequential sampling scheme is shorter than that using a combination of sampling methods.

The required time for a single sampling plan is long.

e) Intra-batch quality variation If a lot consists of two or more sub-lots from different sources, and there may be substantial differences in quality between the sub-lots, then the sequential sampling scheme follows...

Extracting machine samples is more difficult than the corresponding single sampling scheme.

Weighing the advantages of a small average sample size in sequential sampling schemes against the aforementioned disadvantages, we can conclude that sequential sampling schemes are only suitable for single...

The testing costs for sample products are relatively high.

The choice between single sampling and sequential sampling plans should be determined before the start of batch inspection. During a batch inspection, it is not permitted to...

The shift from one sampling plan type to another occurs because if the actual test results influence the choice of acceptance criteria, the operation of the sampling plan becomes more complex.

Its properties may change drastically.

Although sequential sampling is more economical on average than its counterpart single sampling, for the inspection of a specific batch, it may be less economical.

The cumulative difference (a statistic used to determine the acceptability of a batch) may remain between the accept and reject values for a long time, until the test quantity is very large.

Only in certain situations can a decision be made to accept or reject the application. When using a graphical method, this situation manifests as a stepped curve randomly oscillating within an indeterminate region.

To avoid the above situation, a truncated sample size nt is set before sampling begins.

If the acceptability of a batch is not yet determined when the truncation sample size nt is reached, the test is terminated, and the truncation acceptance value and truncation rejection value are used to determine acceptance.

Whether or not the batch is accepted.

Although truncation alters the operational characteristics of a sequential sampling scheme, this document considers these changes when determining the operational characteristics of the sequential sampling scheme.

The sampling method is truncated, therefore the truncation criterion is an integral part of the sampling scheme provided in this document.

ISO 3951-5 also provides a sequence sampling inspection protocol for metrology. However, the design principles of these protocols differ from those in this document.

The fundamental differences are as follows. The sampling plan in ISO 3951-5 is a supplement to the ISO 3951-1 sampling inspection system for metrological acceptance.

This corresponds to the commonly used ISO 2859-1 sampling inspection system for acceptance testing by attributes. Therefore, these schemes are suitable for the inspection of continuous series of lots, i.e., consecutive...

The length of the subsequent batches is sufficient to allow the use of the transfer rules of the ISO 3951 system. This applies to the transfer rules in the ISO 3951-5 sequential sampling scheme.

The only means of protecting users is through stricter sampling inspection criteria or suspension of sampling inspection. However, in some cases...

Under these circumstances, both producer and user risks need to be strictly controlled. For example, risks may arise due to regulatory reasons, proving the quality of the production process, or hypothesis testing.

This situation arises when sampling is performed. In this case, selecting a sampling plan from the ISO 3951-5 sampling plan might be...

Inappropriate. The sampling plan in this document is designed to meet these specific requirements.

Measurement-based truncated sequential sampling inspection procedures and sampling tables (Applicable when the standard deviation is known)

1 Scope

This document specifies the measurement sequential sampling inspection plan and procedures for discrete individual products.

The sampling plans in this document are indexed by producer risk points and consumer risk points. Therefore, these plans are applicable not only to verification Sampling is also applicable to the more general statistical hypothesis testing of proportions.

This document provides a sequential evaluation procedure for test results. Using this procedure, when the quality of a batch of products supplied by the manufacturer does not meet specifications, [further action should be taken].

When a request is made, the probability of acceptance is very low, which can encourage the manufacturer to provide a batch of higher quality products. At the same time, by specifying the acceptance probability of inferior batches (or processes), the upper limit of the rate is used to protect the user.

The sampling plan in this document is designed based on the following conditions being met.

a) The inspection procedures in this document apply to consecutive batches of discrete individual products, i.e., all products are manufactured by the same producer and produced in the same manner.

The process is provided. In this case, sampling a particular batch is equivalent to sampling the process. If there are different producers or production processes...

In this case, this document will be applied to each production party or production process.

b) Consider only a single quality characteristic x of the product, which must be measured using a continuous scale.

c) Measurement error is negligible relative to the standard deviation of the production process (i.e., the standard deviation does not exceed 10% of the process standard deviation).

d) The production process is stable (statistically controlled), the standard deviation of the quality characteristic value x is known, and the quality characteristic value x follows a constant.

It follows a normal distribution or approximately follows a normal distribution.

Note. The sampling inspection procedures in this document are not applicable to batches in which nonconforming products have been pre-screened.

e) If the contract or standard specifies an upper specification limit U, or a lower specification limit L, or both, for the product quality characteristics, then...

The product is considered合格 (qualified) only if the measured quality characteristic x satisfies one of the following inequalities.

1) x<=U (i.e., not higher than the upper specification limit);

2) x >= L (i.e., not lower than the lower specification limit);

3) L<=x<=U (that is, the quality characteristic value is between the lower specification limit and the upper specification limit).

Cases 1) and 2) are called unilateral normative limits, and case 3) is called bilateral normative limits.

If two-sided specification limits are applied, this document assumes that both specification limits are equally important for the product's conformity, or assumes that both specification limits are equally important for the product's conformity.

Consider them separately. In the first scenario, the percentage of combined nonconforming items exceeding both specification limits is controlled; this is known as combined control.

In the second case, the percentage of nonconforming products exceeding each specification limit is controlled separately; this is called discrete control.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

ISO 3534-1 Vocabulary and Symbols for Statistics – Part 1: General Statistical Terminology and Terminology for Probability (Statistics-Vo-Note. GB/T 3358.1-2009 Statistical vocabulary and symbols - Part 1: General statistical terminology and terminology used in probability (ISO 3534-1:2006) IDT)