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RE: Extinction



I just remembered a shortcut for computing the hypergeometric,
and applied it to my first case in the prior letter. (Even the
shortcut is too tedious to do by hand for the other cases).

For 40 species, 36 becoming extinct, and 19 species of dinosaurs,
the probability is 6.5%.  This fails to reject the null hypothesis
at the 5% level. Thus the data are consistant with the extinction
of the dinosaurs being random within the high extinction rate group.

Thus, the data seem to be consistant with a mixed bias and stochastic
model with at three levels of susceptiblility (~10%, ~50%, & ~90%).


swf@elsegundoca.ncr.com         sarima@ix.netcom.com

The peace of God be with you.