True Progress

Often as a reliability engineer, or anyone responsible for researching the reliability of an item, or calculating it, you will find oversimplified published data giving you the impression that reliability is an unchanging physical property like mass or volume, something intrinsic to the materials included in it. This is actually the common sense approach; we know an old thing is less reliable than a new copy of the same thing. But, this common sense gets argued out of us when we are faced with reconciling tables of MTBF (mean time between failures) values, nines (i.e. 0.99999, a measure of reliability), failure rates and other things. Let’s get back to the common sense approach, but with math. Read the rest of this entry »

So, you’ve got a design that you want to prove is better than the existing design from your own or another company. What’s the most efficient, fastest way to get to that answer with a very small sample size? Whle there may be several options you have, including accelerated testing, they each can have their benefits and drawbacks. Here, I will advocate for zero-failure testing as a realistic and useful option, especially since it is something we often do anyways, but without the mathematical justification. Read the rest of this entry »