| Measuring "per participation decision" often makes more sense than "per participation hour" when deciding whether to do an activity. (It could be shortened to "per event", defining an "event" to be the result of one decision.) In explaining the choice of per-hour, the author gave the example of choosing either an afternoon riding a mountain bike or an afternoon flying a sailplane. The example works because they involve about the same number of hours. But it's also the same number of decisions, so per-event works just as well there. Per-event fixes distortions for quick activities, where durations are meaningless because they're dominated by setup time that isn't counted (or alternatively, the risk varies by multiple orders of magnitude depending on whether you count the overhead). The chart shows summiting Everest as being 100x safer than base jumping. But if you're deciding which activity to do, it's more relevant to compare risk per-summit to risk per-jump-trip (say, 5 jumps?) or even risk per-jump, since you can calibrate the number of jumps on your trip based on your risk tolerance, but you can't do a fractional summit. Using the author's numbers, jumping has a risk of 0.13% per jump, or 0.67% for a trip with 5 jumps. Everest has a risk of 6.5%. So in terms more relevant to decision-making, a decision to summit Everest comes with a 10x higher risk of death than a decision to go base jumping, instead of 100x lower as the chart might lead you to think. |