'Is your tail heavy' is the question raised at 'critical uncertainties' in a recent post.
It might be if you are a risk with some "memory" of the immediate past.
Risk with memory? What does that mean?
- The immediate past influences the immediate future
- The probability of the arrival of an outcome is not time-stationary: as time passes, the probabilities change
- The distribution of the arrival time of an outcome is "heavy tailed", meaning that (usually) with more time: if it hasn't happened it probably won't happen
Project consequences:
- Simple assumptions, like symmetrical bell curves, are unlikely to give a good picture of when a risky outcome may happen
- Testing for an unlikely outcome may be easier and more economical than you might think: run a few tests; if it doesn't fail soon (infant mortality) it likely won't for a long while.
- Early on, consumer electronics exhibited such behavior. (If you could make it a few days, you were likely to make it a few years)
Who knew heavy tails were the cheap way out of expensive testing??!
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