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Archiver > GENEALOGY-DNA > 2008-07 > 1216250781


From: "Dienekes Pontikos" <>
Subject: Re: [DNA] calibrating for common ancestor - QUESTION?
Date: Thu, 17 Jul 2008 02:26:21 +0300
References: <mailman.89372.1215791041.8264.genealogy-dna@rootsweb.com><16EF8B32-C14A-46BE-B2E8-98BBF49A1BBE@vizachero.com><00b401c8e751$19198810$6400a8c0@Ken1><E7842801-7B3F-4C69-8F5C-41608A763CE7@vizachero.com><f3f05ce80807160844t1751d9f7gd25e0e53d2185982@mail.gmail.com><8E2E4B64-AD30-44B2-B549-03E688B5F7A2@vizachero.com><f3f05ce80807161429vb8ff25dwad26faf73879c352@mail.gmail.com><4F99FAA7-AF81-4104-A7ED-6B0ECEA5B0D0@vizachero.com><f3f05ce80807161547v26445037rd75d06c8dee96a04@mail.gmail.com><00d801c8e799$3861df90$6400a8c0@Ken1>
In-Reply-To: <00d801c8e799$3861df90$6400a8c0@Ken1>


That is precisely true, that is why it doesn't make sense to average
over the 5 estimates, since for example the I1 and the J estimate have
a long common component (CT to IJ). They aren't _independent_
estimates of the quantity in question (CT to now).


On Thu, Jul 17, 2008 at 2:11 AM, Ken Nordtvedt <> wrote:
> [[[[ Dienekes, I think you are deliberately trying to remain vague.
>
> When two relatively young clades (relatively recent separate MRCAs) are used
> to to estimate the age back to their joint MRCA who existed very long ago by
> comparison, most of the variance between each pair of haplotypes, one of the
> pair from clade A and the other of the pair from clade B, comes from the
> long common branch line that goes back from clade A MRCA to the joint MRCA
> and then forward on another branch up to clade B's MRCA. All N(A) N(B)
> pairs share this same branch length. So one is very close to doing an
> estimate for the TMRCA for a single pair of haplotypes --- just like
> genealogical applications except one or two orders of magnitude longer
> branch lines.
>
> There is basically a SINGLE estimate. And the confidence intervals are
> evaluated accordingly.
>
> There is the statistical noise in that dominant common and long "V" branch
> line, and there is the somewhat washed out statistical noise within the
> lifetimes of the two relatively young clades A and B. Ken ]]]]]
>
>
>
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