When a product fails in the field, the first reaction is often to identify someone to blame. More often than not, the finger is pointed at the design engineer who created the product or the laboratory that tested and certified it. While this may seem like a logical conclusion, it rarely reflects the complete picture. Product reliability is influenced by a combination of engineering decisions, manufacturing quality, operating conditions, user practices, and environmental stresses. Looking at only one part of the chain often leads to incorrect conclusions.