Why Reliability? Reliability has several definitions, mostly covering some likelihood expression of functionality under certain conditions and a given timeframe. And designers and manufacturers often put significant effort into preventing failure. But this begs the question of “why?” The answer is that reliability is a potential benefit to the user and, through sales and profit, to the supplier. Benefits come in the form of safety, of the product confidently delivering its intent, and of lowered operating costs. However, there are also potential downsides, of a higher up-front cost, changed aesthetics, less performance, etc. And, sales may be driven by these more visible attributes. Hence, benefits to the supplier of maybe increased investment (to deliver assured high reliability) might …