Way to quantify the performance of a machine or part.
MTBF = (Total Time of all Parts run) / (Total number of failures)
Good if all parts fail.
Bad if very few of the parts fail. It is very deceptive in this case.
If you run 3 of them for a total of 240 hours, and all 3 fail, you have a MTBF of 80 hours per failure. Makes sense.
If you run 100 of them in an application where the job is complete after 50 hours, at which point you don't run it again, it is possible that only 10 or so will fail. MTBF could be about (90*50 + 10*25) / (10) = 475 hours per failure. This is insane, since you would be lucky if a single tool made it to 200 hours or continuous operation.
2. In biology, the average lifespan of each individual organism which has a particular set of genes or "environment of luck". An "environment of luck" can be something like all people who fly on a plane, living around individuals who want you dead in the worst way,all people who smoke, or some other demographic.
1. In an average house, it is normal to burn out 3 incandescent light bulbs in a month. Therfore the MTBF is 10 days.
2. Teacher:"King tut only lived to be 19."
Mocking Student:"Wow, his MTBF is in the toilet!"
2. "The MTBF of John Benet Ramsey is quite short."