There’s been a lot of stilted relief coming from science-fictional quarters in the wake of 9.11. No one in the SF world — whose publishing hub is in NYC — was seriously injured in that date’s events. I know hundreds of New Yorkers, all unscathed. In a statistical, six-degree-of-separation world, this seems profoundly odd. How did so many of us escape personal tragedy, or even tragedy at one or two removes? This Slate story explains it.

If the average American knows 290 people, then the World Trade Center victims would seem to know about 1.8 million Americans (and vice versa: about 1.8 million Americans would seem to know a victim). But there is overlap in the networks of the victims. Someone who knew one victim at, say, Cantor Fitzgerald is very likely to have known two or more. Some poor souls lost dozens of friends. The authors account for this with an estimated “lead-in factor”�essentially a measure of non-randomness. The lead-in factor helps adjust for the fact that people who worked at the World Trade Center are likely to travel in the same social circles because they work in the same place, live in the same city, and have similar kinds of jobs.

Link Discuss (via Making Light)