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Archiver > GENEALOGY-DNA > 2007-02 > 1171473208


From: "Elizabeth O'Donoghue" <>
Subject: Re: [DNA] TMRCA
Date: Wed, 14 Feb 2007 17:13:28 -0000
In-Reply-To: <042FABC6-6E7C-49D0-BCBD-0D75702EECF9@vizachero.com>


Vincent, perhaps you are right that 'the situation is so dire as some have
suggested.'

What calculators do you use? I frequently hear comments that Family Tree's
calculator underestimates - with 30% and double figures used as how much.
Dennis Wright was kind enough to give me the Excel formulas he used to reach
the age for his Irish Type III haplotype. I believe these formulas used
Zhivotovsky's calculation method, but I don't know the SD/probability
associated with it. When I used them, the TMRCA's compared to FT were fairly
comparable, albeit slightly longer, for quite closely related individuals,
but were wildly disparate for individuals with greater genetic distances.
And if there was a genetic distance of more than one at any particular DYS,
even if quite close otherwise, the distance shot up dramatically.

Perhaps the size of my different groups within the project is less than
ideal, but the TMRCA for the groups is not realistic for what I know of the
family history/geographic proximity of the members (nevermind my quest for
Eoghanacht lineages, which is a different issue).

I appreciate your advice.

Elizabeth







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