Measuring lethality in reduced expected heartbeats

Some of us here are already fa­mil­iar with Micro­morts—a unit that stands for a 1 in a mil­lion chance of dy­ing. The wikipe­dia page lists a num­ber of sam­ple val­ues. One ob­vi­ous ex­am­ple is that smok­ing 1.4 cigarettes is one micro­mort. This is a good tool for com­par­ing the rel­a­tive dan­ger­ous­ness of ac­tivites—for ex­am­ple, if you fly in a jet in the US, your micro­morts per mile from in­creased back­ground ra­di­a­tion are twice the micro­morts per mile from ter­ror­ism. And you can com­pare ac­tivi­ties to baseline av­er­age risks of death, given as about 39 per day (av­er­aged over all age groups and sexes).

How­ever, peo­ple suck at imag­in­ing small prob­a­bil­ities. So a differ­ent unit, which we used in a group ex­er­cise at the Sec­u­lar Sols­tice in Leipzig, is the num­ber of ex­pected fu­ture heart­beats. While Micro­morts are a step away from em­piri­cal re­al­ity, ex­pected heart­beats are an­other step in the same di­rec­tion. But the con­cept got good feed­back, it makes peo­ple think about life in a new way, so I thought I’d just share it here.

The av­er­age hu­man heart gets to beat about 2.5 billion times—about 100000 times per day. So a micro­mort is around 2500 ex­pected heart­beats. So you can trans­late, say, smok­ing a cigarette into a cost of about 1800 ex­pected heart­beats (or about 80 sec­onds of life ex­pec­tancy). And maybe that’ll help peo­ple op­ti­mize their be­hav­ior in ways that Micro­morts, due to their micro­prob­a­bil­ity na­ture, aren’t very good at do­ing es­pe­cially for those who aren’t very ha­bit­ual Bayesi­ans.