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Archiver > GENEALOGY-DNA > 2001-12 > 1008432041


From: Patrick Guinness <>
Subject: [DNA] MRCA calculator
Date: Sat, 15 Dec 2001 16:00:42 +0000


Dear Ann,

That's a great calculator and paper, if I could understand it
all. While the Y-mutation rate is 0.0012 per locus per generation,
the probability of observing a mutation at any one of several loci is
apparently higher.

In Bianchi's paper on Amerindians (freely downloadable from
the AJHG) at -

http://www.journals.uchicago.edu/AJHG/journal/contents/v63n6.html

at pages 1862 - 1871,

he looked at 7 loci and applying a binomial distribution (page 1867,
left column) he found that the probability of observing a mutation at
any of the 7 loci is 0.0083.

Obviously 0.0083 is a good bit higher than 0.0012 - that much
I do understand.

Could MathMan be prevailed upon to work out that formula for
studies at 10, 12, 17 and 21 loci, for those of us who are
algebraically-challenged or like me just plain innumerate?

Looking at say one mutation / repeat either side of a
middling result, to keep it simple.

(I don't even know what a binomial distribution is either.)

Further, I suggest that anyone interested in North- &
South-Amerindian Y dna should download that paper.

PG

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