Reminds me of a humorous/sarcastic joke made by an engineering in the printer industry years ago.

People ask for two figures on the big heavy duty cycle printers, MTBF and MTTR.

They all focus on MTBF (mean time between failures) which is a bit like russian roulette. Failure could happen at any time given the environment, use, power quality because the MTBF is a paper calculation based on the components in most cases. So they are making the decision based on this as the most important value. If I want to improve this I simply take anything good but not critically necessary out of the system. Less components means less elements to go wrong. Smoothing components, protection, fuses, test points, not making it better but getting a better number. I have a great MTBF but a nasty bit of kit which is more likely to pop it's clogs if under duress.

The MTTR (mean time to repair) is much more interesting. Do you have to dismantle the entire thing to fix one part. In truth the more reflective of good value. If one bit breaks the entire system around it is stopped, so the sooner it is fixed the sooner your entire investment is resolved and making money again. People never pay attention to the MTTR.

I am starting to get the feeling that legislation, whilst well intended, is producing a third measure.TCTW or too complex to work. How high up the TCTW scale are products becoming.


Everyone loves a Morgan. Even me, unless it's broken again.