The Six Sigma Handbook, Revised and Expanded, 2nd Edition

20.6. HOW CAN WE CONTINUE TOWARDS PERFECTION?

Years ago there was a popular concept in the area of quality known as the "Acceptable Quality Level," or AQL. AQL was a term used to define the long-term defect rate for a supplier's process that was acceptable to the customer. AQLs were widely used in the military procurement area, and I became heavily involved with them when I took a position as Quality Engineer in a missile production facility. I have previously worked for commercial operations where I had experience successfully implementing statistical process control methods. However, when I tried to introduce the approach in a production area at the missile manufacturer I was told it wasn't necessary because "We already meet the AQL." I did ...