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Archiver > GENEALOGY-DNA > 2009-12 > 1260679972


From: Al Aburto <>
Subject: Re: [DNA] R-U152 and R-L21 on the European Continent
Date: Sat, 12 Dec 2009 20:52:58 -0800
References: <200912130345.nBD3jXOY012290@mail.rootsweb.com>
In-Reply-To: <200912130345.nBD3jXOY012290@mail.rootsweb.com>


You way I see it is, if you use fast mutating markers you are going to
get a younger age --- if you use slow mutating markers you are going to
get an older age. If you use a mix of the two you are going to get an
age in between ... I think you have to keep the fast mutating markers to
get the "right" mix (whatever that is)...
Al

> Tim Janzen wrote:
> Dear John,
> Thanks for the background information. The problem is that you must
> throw away the fast mutating markers because their variance is saturated if
> you are going to attempt to calculate interclade TMRCA estimates that are
> anywhere close to the true TMRCAs for subclades or haplogroups that are
> 20,000 years old or older. There is no way around it. As I pointed out in
> my message in July at
> http://archiver.rootsweb.ancestry.com/th/read/GENEALOGY-DNA/2009-07/12473842
> 75 and in my earlier messages today, TMRCA estimates based on haplotype
> datasets that include the fastest mutating markers in the 67-marker FTDNA
> panel clearly skew the TMRCA estimates to be lower than they rightly should
> be. I would rather accept a wider confidence interval and know that there
> is a reasonable probability that my interclade TMRCA estimates are accurate
> than to include a lot of fast mutating markers that are clearly skewing the
> TMRCA estimates to be lower and thus clearly creating TMRCA estimates that
> must certainly be incorrect. Confidence intervals are only helpful if you
> have correct assumptions and processes for the calculations.
> Below I am including the 95% confidence intervals for the interclade
> TMRCA estimate for the node of haplogroups A and B using your estimated
> mutation rates:
>
> 10 slow markers: 147279 years (95% confidence interval is 77533 years)
>
> 10 slow medium markers: 78714 years (95% confidence interval is 32217
> years)
>
> 10 medium markers: 8396 years (95% confidence interval is 6175 years)
>
> 10 medium fast markers: 21794 years (95% confidence interval is 6750 years)
>
> 10 fast markers: 13847 years (95% confidence interval is 3479 years)
>
> 50 markers: 35245 years (95% confidence interval is 3070 years)
>
> 10 YHRD markers using YHRD mutation rates: 8811 years
> (95% confidence interval is 5657 years)
>
> 24 slow markers: 77576 years (95% confidence interval is 22008 years)
>
> Note that all of the TMRCA estimates above that have relatively
> tight confidence intervals are all clearly inaccurate. The only TMRCA
> estimates that are likely to be close to the true TMRCA are the three with
> the widest confidence intervals (the 10 slow markers, the 10 slow medium
> markers and the 24 slowest markers).
>
> Sincerely,
> Tim
>
> -----Original Message-----
> From:
> [mailto:] On Behalf Of John Chandler
> Sent: Saturday, December 12, 2009 1:03 PM
> To:
> Subject: Re: [DNA] R-U152 and R-L21 on the European Continent
>
> It is important to quote uncertainties along with estimates. In the example
> I gave above, the 1/10 estimate was 0.1 +/- 0.1 for the individual
> experiments, encompassing the 1/6 mean-value estimate comfortably. The
> combined experiment gave the same estimate, 1/10, but the uncertainty was
> reduced to +/- 0.07, still comfortably encompassing the MVE 3/22.
> As it happens, if you throw away all the
> fast markers, the TMRCA uncertainty goes to pot, and that is why a
> result based only on the slowest markers is not very reliable in any
> case -- because it is too uncertain.
>
> John Chandler
>
>


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