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What Is the Confidence Level when Working with AQL Tables?

August 1, 2019

What Is the Confidence Level when Working with AQL Tables?

A reader wrote to me and asked the following question about sampling plans by attributes: What is the "Confidence Level" when using the AQL Tables? How can we determine what the confidence levels are, and are there formulas we can use? That's a valid question. When playing with statistics, one often mentions a confidence interval. For example, "90% of the time, the value will be between 34.5 and 66.0". In theory, I guess one could do the same with the values in the AQL tables. There is a … [Read more...]

Filed Under: Quality Control Tips Tagged With: AQL, Aql Tables, confidence level, confidence levels, quality inspections, quality inspectors, random aql inspection, random sampling aql inspection

A Simple AQL Calculator To Prepare Your Product Inspections

May 13, 2019

A Simple AQL Calculator To Prepare Your Product Inspections

One of our developers prepared this simple AQL calculator for Sofeast. You can use it instead of reading the AQL tables to quickly produce your sample size and permissible defect number. … [Read more...]

Filed Under: Quality Control Tips Tagged With: AQL, aql calculator, aql limit, Aql Tables, product inspections, QAQC, quality inspections, random aql inspection

The Special Inspection Levels in the AQL Tables

April 9, 2019

The Special Inspection Levels in the AQL Tables

A few years ago I wrote about the inspection levels, but I regularly notice that some people are confused about the "special" levels (S1, S2, S3, and S4). Here is what the ISO 2859-1 standard says (emphasis is mine): The inspection level designates the relative amount of inspection. Three inspection levels, I, II and III, are given in Table 1 for general use. Unless otherwise specified, level II shall be used. Level I may be used when less discrimination is needed or level III when greater … [Read more...]

Filed Under: Quality Control Tips Tagged With: AQL, Aql Tables, inspection levels, special inspection levels

What is the “AQL” (Acceptance Quality Limit) in simple terms?

August 28, 2018

what is the AQL

What Does AQL Mean? 'AQL' stands for 'Acceptance Quality Limit', and is defined as the "quality level that is the worst tolerable" in ISO 2859-1. It represents the maximum number of defective units, beyond which a batch is rejected. Importers usually set different AQLs for critical, major, and minor defects. Most Asian exporters are familiar with this type of setting. For example: "AQL is 1.5%" means "I want no more than 1.5% defective items in the whole order quantity, on average over … [Read more...]

Filed Under: Quality Control Tips Tagged With: Acceptable Quality Limit, AQL, Aql Tables, inspection, Quality, Sampling

Why the AQL tables are not in favor of the buyer

September 30, 2013

Why the AQL tables are not in favor of the buyer

This is the third and last video about the ANSI tables (also known as “AQL tables”). As I explained in the last video, these sampling schemes were designed for very stable relationships, where the manufacturer keeps making the same products and keeps shipping them regularly (e.g. twice a month) to the same customer. As a consequence, the assumption is that quality is under control. And an inspection is used to catch the big accidents. What it means is that the statistics are way, way … [Read more...]

Filed Under: Quality Control Tips Tagged With: ANSI/ASQ Z1.4, AQL, Aql Tables, defects, product inspections, qa, QC, quality inspections

How to choose an AQL limit?

August 10, 2012

How to choose an AQL limit?

A few months ago, I wrote an explanation about the "AQL": what it is and how to use it. I also listed a few frequent questions, but it seems like I forgot one of them: What AQL tolerance is suitable to my products? Unfortunately, it is hard to base this on statistical reasoning. So I don't have any definitive answer. The right AQL depends on two things, I think: The market you are selling into, The kind of risk the users run by using/consuming/getting close to your product. 1. … [Read more...]

Filed Under: Quality Control Tips Tagged With: AQL, aql limit, Aql Tables, choosing an AQL limit


Weekly updates for professional importers on better understanding, controlling, and improving manufacturing & supply chain in China.

This is the official blog of Sofeast.com.

This blog is written by Renaud Anjoran, an ASQ Certified Quality Engineer who has been involved in Chinese manufacturing since 2005.

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