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Archiver > GENEALOGY-DNA > 2010-02 > 1267389791


From: "Tim Janzen" <>
Subject: Re: [DNA] : low variance MRCA dates for P310cladesinItalyandSEEurope
Date: Sun, 28 Feb 2010 12:43:11 -0800
In-Reply-To: <629F5214-14E0-419C-84C3-6F5DA59EA13C@vizachero.com>


Dear Vince and Ken,
I am fine with referring to these estimates as intraclade
coalescence ages if that is the overall consensus. I have tried to point
out in various messages in the past that intraclade estimates often
underestimate the true TMRCA based on testing I have done of haplotypes
generated by Sandy Paterson previously. That said, intraclade estimates
probably don't underestimate the true TMRCA by a lot as long as the sample
size is adequate. In any case the term TMRCA has been used on this list for
a very long time and I don't see any reason not to use it as long as we know
what we are referring to. It is also a term that is used on Dean McGee's
utility at http://www.mymcgee.com/tools/yutility.html which has been in use
for quite a few years. The terms coalescence age and divergence age haven't
been in widespread use on this list over the years. The term TMRCA seems to
be in more common use. In my opinion it is more important that we make sure
we indicate whether we are doing intraclade or interclade estimates, since
the methodology between the two is definitely different.
Sincerely,
Tim

-----Original Message-----
From:
[mailto:] On Behalf Of Vincent Vizachero
Sent: Sunday, February 28, 2010 12:23 PM
To:
Subject: Re: [DNA] : low variance MRCA dates for P310
cladesinItalyandSEEurope

Just because two terms have been used interchangeably doesn't mean
they should be or that they actually have the same meaning.

In this case, we all know that intraclade variance does not lead to an
actual TMRCA estimate so calling out the distinction is probably smart.

VV


On Feb 28, 2010, at 3:14 PM, Tim Janzen wrote:

> Yes, they are coalescence age estimates. I agree with Steve
> Bird that these two terms can be used interchangeably.



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