ASQ/ANSI Quality Control Standards Z1.4 & Z1.9
What is the Z1.4 Standard?
ANSI/ASQ Z1.4-2003 (R2013): 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.
What is the Z1.9 Standard?
ANSI/ASQ Z1.9-2003 (R2013): 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.
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.
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.
Z1.4 & Z1.9 Standards Training
- Improvement Tools & Techniques: Charts, Controls, Diagrams, Improvement Methods, Sampling and Problem Solving
- Certified Quality Engineer Certification Preparation
Quality Engineer Certification
Books on Quality Control Standards
- Zero Acceptance Number Sampling Plans, Fifth Edition
- Glossary and Tables for Statistical Quality Control, Fourth Edition
Articles on Acceptance Sampling
- Comparing Acceptance Sampling Standards, Part I, Quality Engineering, January 2013
- Comparing Acceptance Sampling Standards, Part II, Quality Engineering, April 2013
- Caveats Regarding the Use of Statistical Analysis (members only), World Conference on Quality and Improvement, May 2009
- Attribute Acceptance Sampling as a Tool for Verifying Requirements Using Monte Carlo Simulation (members only), Quality Engineering, April 2009
- A Sampling Plan for Contact Auditing in Call Centers (members only), World Conference on Quality and Improvement, May 2010
- Evaluating and Implementing 3-Level Control Charts, Quality Engineering, July 2006