21Chapter two: The distracting jungle of reliability concepts
same results, the condence level for that conclusion would increase to
around 90%.
2.4 Dimensional differences between
quality defects and failures
Generally, quality-related trouble appears for one of three reasons:
1. Customer misuse of the product
2. Nonconformance to specications during manufacture
3. Mistakes or incompleteness in design specications or manufacturing
An analogy of the rst case would be a car crash due to the driver’s
dozing off. In the second instance, being out of specication or having
a quality defect would obviously induce poor performance or failure in a
product.
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Finally, any mistakes or omissions in design or manufacture
will induce fa ...