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ASQ/ANSI Quality Standards Z1.4 & Z1.9


What is the Z1.4 Standard?

Standard iconANSI/ASQ Z1.4-2003 (R2018): Sampling Procedures and Tables for Inspection by Attributes is an acceptance sampling system to be used with switching rules on a continuing stream of lots for Acceptance Quality Limit (AQL) specified. It provides tightened, normal, and reduced plans to be applied for attributes inspection for percent nonconforming or nonconformities per 100 units.

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What is the Z1.9 Standard?

Standard iconANSI/ASQ Z1.9-2003 (R2018): Sampling Procedures and Tables for Inspection by Variables for Percent Nonconforming is an acceptance sampling system to be used on a continuing stream of lots for Acceptance Quality Limit (AQL) specified. It provides tightened, normal, and reduced plans to be used on measurements which are normally distributed. Variation may be measured by sample standard deviation, sample range, or known standard deviation. It is applicable only when the normality of the measurements is assured.

  1. Soft cover print version
  2. E-standard (PDF)
  3. Site license for your organization's intranet

History of Z1.4 & Z1.9

Read an overview on sampling, which describes the origins and purposes of the statistical standards ANSI/ASQ Z1.4, which establishes sampling plans and procedures for inspection by attributes, and ANSI/ASQ Z1.9, which establishes sampling plans and procedures for inspection by variables.

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Purchase ANSI/ASQ Z1.9

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Save 25% with Purchase of Both Standards

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Learn More About Z1.4 and Z1.9

Visit the Ask the Standard Experts blog for help with your questions about the Z1.4 and Z1.9 standards.

View previously answered questions on Z1.4 and Z1.9, or submit your own question.

Z1.4 & Z1.9 Standards Training

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Articles on Acceptance Sampling

Comparing Acceptance Sampling Standards, Part I (Quality Engineering) In this first part of a two-part series, common attribute sampling standards are discussed and compared.

Comparing Acceptance Sampling Standards, Part II (Quality Engineering) In part two of this series, the discussion will shift to the development of variables sampling standards which find their linkage to a military standard, and will serve to discuss and compare these derivative standards in the manner in which attributes standards were covered in Part 1.

Attribute Acceptance Sampling as a Tool for Verifying Requirements Using Monte Carlo Simulation (Quality Engineering, members only) Acceptance sampling can be adapted to verification problems that rely on the outcomes of stochastic experiments. This article shows how the technique is used to verify a problem of probabilistic design requirements using Monte Carlo simulation.

Evaluating and Implementing 3-Level Control Charts (Quality Engineering) Some quality measures may use three or more discrete levels to classify a product characteristic. This study uses this scheme and methodology to evaluate and implement 3-level control charts.

More acceptance sampling articles and content

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