Improving Product Reliability and Software Quality, 2nd Edition

2Barriers to Implementing Hardware Reliability and Software Quality

2.1 Lack of Understanding

Probably the greatest barrier to improving reliability is the lack of understanding of what reliability actually means. Much of the resistance you will experience in implementing reliability will come from individuals who believe that quality and reliability are the same thing. But as we have shown before, they are not. Quality is conformance to specification, while reliability is quality over time. Reliability from a customer perspective is that “the product works the way it was supposed to work for its desired period of use.” Before you start improving reliability, you must be aware of what you are improving.

As a practical matter, most companies have quality improvement processes in place throughout their manufacturing process. Understanding the difference between quality and reliability is the key, because if you don't understand the difference, you may just be improving your product quality while not impacting your product's overall reliability at all. How can you separate the two?

First, focus on what's been going wrong in the manufacturing processes. Then take a look at the data that describe what has been going wrong. Review the data to see how the problem has been corrected. If it has been corrected by anything other than a design or process change, all you did was manage the process to maintain conformance to a specified parameter. You maintained conformance to specifications. ...