Schneier on Security | Bruce Schneier | Micromorts(1) Yes, this is a neat idea. The analogy to using grams (or pounds) rather than tons makes a lot of sense.
Here's a great concept: a micromort:
Shopping for coffee you would not ask for 0.00025 tons (unless you were naturally irritating), you would ask for 250 grams. In the same way, talking about a 1/125,000 or 0.000008 risk of death associated with a hang-gliding flight is rather awkward. With that in mind. Howard coined the term "microprobability" (μp) to refer to an event with a chance of 1 in 1 million and a 1 in 1 million chance of death he calls a "micromort" (μmt). We can now describe the risk of hang-gliding as 8 micromorts and you would have to drive around 3,000km in a car before accumulating a risk of 8 mt, which helps compare these two remote risks.There's a related term, microlife, for things that reduce your lifespan. A microlife is 30 minutes off your life expectancy. So smoking two cigarettes has a cost of one microlife.
(2) People are tremendously bad at reasoning numerically about fractions. For instance, people tend to see the difference between 1/50,000 and 1/100,000 as the same as that between 1/200,000 and 1/250,000. This may help alleviate that problem since it holds the denominator constant and presents the numerator to people to reason about.
(3) Perhaps we need a unit like the horsepower: some sort of real world baseline for risk to which we can refer. Maybe everything can be compared to lightening strikes, so the chance of dying in a helicopter crash might be 0.25 L-strikes if four times as many deaths are caused by lightening as helicopter crashes. (I'm totally guessing about those values.)
My first thought was deaths-for-falling-down-stairs, but that is not nearly constant over time or across cultures. Plus I can't think of an easy abbreviation like "L-strike".
(4) I think micromorts and microlives may give more ammunition to scaremongers. It's already easy enough to scare people about tiny risks. I sure don't want to make it any easier. We would have to do some surveys to find out, but I suspect 8.6 micromorts sounds scarier than a 1 in 116,000 chance of dying.
(5) You can gather pretty good statistics for the chance of dying from hang gliding accidents, and get a pretty precise measure of the micromorts involved. Determining microlives involves much more sophisticated actuarial calculations, and I'm pretty certain it will end up being much less accurate. I would be very skeptical of someone who could tell me with any precision at all how many microlives eating a sunny side up egg or medium rare steak will cost me.
I'm all for doing things scientifically and quantitatively, but I am wary of pseduo-science and false precision. "All large calculations are wrong," as a wise man once said. I do not want to give technocrats and professors hungry for grants any more reason to go in front of Congressional hearings to talk about how they've calculated that allowing Americans to smoke weed/drink wine/drive Toyotas/use Sidecar for ride-sharing/eat imported haggis/etc is costing them 59.463271 microlives each.
Yeah, this is a bit immaterial. Micromorts/microlives are still a good idea. I'm just pointing out that they may be used for Evil as well as Good.