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From: "Ken Nordtvedt" <>
Subject: Re: [DNA] : low variance MRCA dates for P310cladesinItalyandSEEurope
Date: Sun, 28 Feb 2010 21:34:59 -0700
References: <201003010245.o212joNm018481@mail.rootsweb.com>


It never pays to stack the samples with anything --- close relatives or
purported outliers. Any bias in the sample selection will probably produce
a bias in the coalescence age.

I go out of the way to not take multi-members of surname projects, because
the nature of such data collections is stacked in the direction of close
relatives (late separating branches).


----- Original Message -----
From: "Tim Janzen" <>

> Dear Ken,
> It is true that the relationship between intraclade coalescence age
> estimates and the true TMRCA is rather fuzzy, but generally speaking it
> would appear that intraclade coalescence ages frequently underestimate the
> true TMRCA. Thus we should strive to avoid stacking the dataset with too
> many closely related haplotypes that we know will be skewing our
> intraclade
> coalescence age estimates to be lower than they otherwise would be.
> Sincerely,
> Tim



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