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Archiver > GENEALOGY-DNA > 2004-01 > 1073010864


From: Colin Ferguson <>
Subject: [DNA] MRCA calculations useless for individual cases
Date: Thu, 01 Jan 2004 18:34:24 -0800
References: <200401020102.i0212mKg014274@lists5.rootsweb.com>
In-Reply-To: <200401020102.i0212mKg014274@lists5.rootsweb.com>


David,
I think you're correct from at least one point of view. I think that the
MCRA computations assume a random sample. In a surname project the
sample is no longer random. If the surname is known the MCRA is tighter
and if not looser; however there does not seem to be a way to say much
tighter or looser - I assume considerably.

I find the concept of MCRA or genetic distance useful in establishing
bounds to the problem. It has shown me that 12 marker test is simply a
'go and no-go' check on a relation. I believe the MCRA calculations
correctly conclude that a 37 marker match is twice as tight as a 25
marker match.
--
Cheers,
Colin Ferguson



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