Percentage Thumb Rules for Quality Costs


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(I asked this on ASQ's forum a few weeks ago, but little discussion. I have seen percentages somewhere, but can't remember where, so I'm hoping someone out there does.)

One of the test answers I was looking at said this: "prevention costs are too low a proportion of the quality costs shown."

Are there good thumbrules for percentages WRT total cost for prevention, appraisal, internal and external failure costs?

Thanks for your help!


Jen Kirley

Quality and Auditing Expert
I am not aware of an optimal proportion set, but there are a number of models showing the concept of spending too much to prevent (as some consider with in Phillip "Zero Defect" Crosby) versus too little, which results in costly, spectacular failure (the Ford Pinto, among others).

Those are old models though. These days it is also important to consider internal and external costs of poor quality. Dr. Juran called them waste, and declared as much as 20% of sales was lost to cost of poor quality.
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