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Archiver > GENEALOGY-DNA > 2007-06 > 1182442351


From: "Peter A. Kincaid" <>
Subject: Re: [DNA] TMRCA Corrections
Date: Thu, 21 Jun 2007 13:12:31 -0300
References: <004101c7b33f$d2296bf0$6400a8c0@Ken1><REME20070620221136@alum.mit.edu><012b01c7b3ba$b580baf0$6400a8c0@Ken1>


If we take 30 years to a generation then most surname
projects are dealing with a timeframe of within 30
generations. Thus, it seems that you are suggesting
that the TMRCA correction would be quite significant
(given the increase going from 400 G to 150 G) for
anyone testing for genealogical purposes. Furthermore,
if the pattern for 200 generations is comparable
for 30 generations then, within a surname cluster, an
outlier's TMRCA could potentially be overstated.
Either that or there is no application to surname projects.

The whole concept does not help one decide at what
point, in terms of mutations from the node of a cluster
within a surname project, is a non paternity event the
likely scenario.

Peter


----- Original Message -----
From: "Ken Nordtvedt" <>
To: <>
Sent: Thursday, June 21, 2007 1:14 AM
Subject: Re: [DNA] TMRCA Corrections


>
> ----- Original Message -----
> From: "John Chandler" <>
>
>
> This means that the
>> tables for cases even just a few steps away from modal will have
>> to be carefully calculated with proper weighting. I hope you are
>> proceeding with these calculations, or at least a sample.
>
>
> Here's an illustrative sample case. m = .0025 Clade 200 generations old
>
> I considered two identical haplotypes but displaced from the founder's
> haplotype by one step mutations at fraction F of its markers. Below I
> give
> the rescaling of the (mean)TMRCA and accompanying percentile confidence
> boundaries for various values of fraction F of one step mutations from the
> central founder's haplotype.
>
> F = 0 161%
> F = .2 123%
> F = .4 100%
> F = .6 84%
>
> So the tendency of TMRCAs moving from greater than traditional values for
> TMRCA to less than traditional values for TMRCA as one's haplotype pair
> moves away from the founder's central haplotype is being carried out.
>
> Ken
>
>
>
>
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