It's not quantified though. Also, it's pretty bad engineering practice to rely on implied risk; it's much more preferred to explicitly state your risk assumptions.

E.g., one of the problems with the Shuttle disasters is that the implied risk was understood differently at various levels. (Making numbers up here but directionally accurate) After the fact, managers thought there was a 1/1000 risk of catastrophic failure while engineers put it a 1/172.