Manning, I enjoyed your ice age comments, and think this is a very good topic to discuss.
YOU SAID: A similar pet peeve of mine is the frequency of occurrence versus the severity of the event or hazard. One pundit proposes that there is a zone of acceptability between the graph of these two, but I believe that hazard reduction is for safety and frequency reduction is the domain of insurance statisticians. Just to play devil's advocate, suppose I've been selling fairly safe "widgets" and have 50% of the market. I redesign it to make it ultra-safe, safer than any other widget on the market. But in doing so I price my widgets out of the market, and people buy the competitors widgets which are less safe. As a result, total deaths and injuries due to widgets increases: my safer design lead to decreased overall safety! The really tough question is, how safe is safe enough? But I agree with your pundit: we must sometimes weigh hazard frequency against severity. Check out functional safety standards such as IEC 812 Procedures for failure mode and effects analysis (FMEA), IEC 1025 Procedures for fault tree analysis, draft std. BS EN 1441 (94/506771 DC), Medical Devices-Risk Analysis, VDE 0801, Principles for Computer in Safety-Related Systems.
