What is mean time between failures (MTBF)?

In reliability analysis, MTBF is the average time between failures for a repairable system with a constant failure rate. The higher the MTBF, the more reliable the product.

In Minitab, MTBF has these uses:
  • As a parameter estimate for a growth curve. For example, the MTBF for a type of engine is 297.7 hours. This statistic means that, on average, engine failures occur approximately every 298 hours.
  • To compare multiple repairable systems. For example, do the engines manufactured in Plant 1 have the same MTBF as those manufactured in Plant 2?