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Archiver > GENEALOGY-DNA > 2009-12 > 1260854757


From: "Tim Janzen" <>
Subject: Re: [DNA] R-U152 and R-L21 on the European Continent
Date: Mon, 14 Dec 2009 21:25:57 -0800
In-Reply-To: <009701ca7cd8$c77febb0$6400a8c0@Ken1>


Dear Ken,
Thanks for bringing this up. No, I haven't yet changed the "2" to
the correct "4" in the downweight. As I recall, we had some brief
correspondence about that issue this summer, but I haven't had much time
this fall to make any modifications to the program. I thought about this
issue again last night when I was posting my messages and was thinking about
contacting you about this again.
I'll go back and add an option to my program that includes the
correct "4" in the downweight. It will be interesting to see how much this
impacts the age estimates. I suspect that it won't affect the ages of
younger subclades all that much, but it will probably have a significant
impact on the ages of old nodes, such as the haplogroup A/B node.
Sincerely,
Tim

-----Original Message-----
From:
[mailto:] On Behalf Of Ken Nordtvedt
Sent: Monday, December 14, 2009 8:16 AM
To:
Subject: Re: [DNA] R-U152 and R-L21 on the European Continent

Have you also implemented the proper downweighting factors in the basic
interclade G estimator? w(i) = 1/[1+4m(i)G] ?
With your interest in the very deepest of the nodes it will prove worthwhile

to have the correct "4" in the downweight.

I used a factor "2" in my Generations2 interclade weighting because I am
mainly interested in node ages where the node was not much older than the
ages of the two clades being compared. So I ameliorated the downweight
somewhat to account for the rapid breakup of the single ancestral lines into

the many branch lines in each clade after their separate MRCAs.

Ken


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