Rational risk assessment is very interesting, but can anyone cite a real life instance where it made a difference?
Look up the history of FMECA (Failure Mode Effects and Criticality Analysis). Everything that has been cited here is an example of it. Like most preventative practices, it's not so much a history of successes, but of failures that either didn't happen or had minimal effect on the system.
As an example; My own disaster planning FMECA:
Probability of occurence:Wildfire (moderate)
Flood (low)
Earthquake (moderate)
Crime (low)
Aviation accidents (low)
Ground vehice accidents (low)
Loss of utilities (moderate)
Severity of occurence:Wildfire (high)
Flood (low)
Earthquake (moderate: based on shake damage maps, building construction, and local geology)
Crime (moderate. Mostly vehicle theft/burglaries)
Aviation accidents (low)
Ground vehicle accidents (low)
Loss of utilties (moderate)
Hazard (risk)index is a combination of Probability of Occurence and Severity of Occurence and determines where I allocate my resources (time, money, space, etc.).
Wildfire (high)
Flood (low)
Earthquake (moderate high)
Crime (moderate)
Aviation accidents (low)
Ground vehice accidents (low)
Loss of utilities (moderate high)
As you can see above, Wildfire is my primary concern, followed by earthquake and loss of utilities, and crime bringing up the back. If I lived out in the Cochella Valley or the Bay Area (Earthquakes), Oakland (Crime), or Mission Valley (Flooding) this would obviously change.