[time-nuts] MTBF/MTTF etc.

[John Green]

The discussion on the merits of failure rate calculations is fascinating. I
was asked by one of our customers to provide MTBF for our products. After
some research, I told them I couldn't provide that data and didn't think it
would be of much use if I did. I asked if MTTF wouldn't be a better figure
and they said "no" but gave no reason why. They asked about failures
reported by our customers over the years. I replied that in 15 or so years
of making that product, we have not received a single report of failure in
the field. In that time, we have made probably 50 million at least, so our
MTBF should be pretty good. The one thing all that ignores is that our
product (molded thick film attenuators) if discovered defective in the field
is just tossed by a technician and a new one installed. They are pretty
reliable though. I just can't say with certainty how reliable.