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*To*: "The Dinosaur Mailing List" <dinosaur@usc.edu>*Subject*: Re: Mass Extinction Statistics*From*: "David Marjanovic" <david.marjanovic@gmx.at>*Date*: Fri, 25 May 2001 14:35:49 +0200*References*: <Pine.OSF.4.21.0105242305340.15938-100000@marlowe.umd.edu>*Reply-to*: david.marjanovic@gmx.at*Sender*: owner-dinosaur@usc.edu

> On Thu, 24 May 2001, David Marjanovic wrote: > > > > I put up 500,000 black dots and 500,000 red dots on my board. I have a > > > cannon that fires 500,000 bullets at once. > > > > I'd rather say you have a big bomb rather than exactly 500,000 individual > > bullets. You let the bomb detonate, and then you look if you find a pattern > > among the unhit dots. > > Well, whatever the delivery mechanism, it should have a random > effect--perhaps more diffuse than a bomb--after all, the placentals are > not all living together in one happy bunker, nor the marsupials. There > are millions (probably) of organisms in many niches. AFAIK there were few niches occupied by meta- & eutherians in LK NA, just everything between shrew, opossum and Tasmanian Devil. > > > Given our assumption of equal population number, equal > > > susceptibility, etc., is this not a fair analogy? And isn't it true that > > > the more dots I have, the greater my chance of reaching 50/50? > > > > The more times you fire the cannon, not the more dots you have. Sorry -- only if you average over the times you fire the cannon, of course. If you, say, double the number of dots, each single dot still has a 50/50 probability of being hit, but the probability that 500,000 particular dots will be hit is, if I'm correct, 0.5^500,000, whereas the probability that 1,000,000 particular dots will be hit is a mere 0.5^1,000,000 -- far, far, far LESS. > Several have said this. Why? What's the difference whether I increase > the population or the number of bolide strikes? Flipping a > flippin' coin a hundred times is the same as flipping 100 flippin' coins > once. But flipping coins is not analogous to the above approximation to an impact. 0.5^500,000^2 (hitting 500,000 particular dots in two tries -- not necessarily the same dots in both tries) is not the same as 0.5^1,000,000 (hitting 1,000,000 particular dots in one try)!

**References**:**Re: Mass Extinction Statistics***From:*John Bois <jbois@umd5.umd.edu>

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