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From: "wim callewaert" <>
Subject: Re: [DNA] age estimations based upon ASD-calculations
Date: Sat, 9 Dec 2006 21:01:39 +0100
In-Reply-To: <00b001c71bac$379c8d40$6400a8c0@Ken1>


I changed the tool according to your remarks.
I checked it within the haplogroup I1a Project and I came to a slightly
different result: first I came to an age of 7423 years, now it was 7387
years.

You also said that not all ASD-formulas are correct, "particularly the one
that guesses a founder's haplotype as part of the process"
Do you mean by that when one starts with calculating the modal haplotype of
a population?

Wim

-----Oorspronkelijk bericht-----
Van:
[mailto:] Namens Ken Nordtvedt
Verzonden: zaterdag 9 december 2006 17:08
Aan:
Onderwerp: Re: [DNA] age estimations based
uponaveragesquareddifferencecalculations

The 37 separate age estimates are not to be made and then averaged. The
ASDs of the 37 markers are to be added together and divided by the sum of
the mutation rates, or equivalently that divisor can be the average mutation

rate times the number of markers, 37. This way of combining the 37 markers
is dictated if you accept that the variance of each marker's ASD is
proportional to its mutation rate, and you accept the "least squares fit"
principle for G estimation.

More later.


----- Original Message -----
From: "wim callewaert" <>
To: <>
Sent: Saturday, December 09, 2006 8:45 AM
Subject: Re: [DNA] age estimations based upon
averagesquareddifferencecalculations


>I used the formula I found on your website.
> In a population I compare each possible pair of STR-values and square the
> difference. I sum up the differences and divide by the total number of
> compared pairs.
> That ASD-result is believed to be = 2*G*M (two times the number of
> generations * mutation rate), so by providing a generation age and a
> mutation rate in the tool, we could infer an age estimation per marker.
>
> The tool does this for 37 markers. The final age estimation for a
> population
> is the average of the 37 age estimations.
>
> Regarding the default mutation rates, I started with the even lower
> Zhivotovsky 0,0007 mutation rate. Each time I calculated an age for a
> population (mostly a haplogroup project) I did the reverse thinking: if
> that
> is the age for that population, it must be that age in each marker and
> then
> I calculated the mutation rate needed to get that age. This brought me to
> upgrade the mutation rates in most markers so that the default average is
> now 0,0012. But I agree that after making a lot more calculations the
> mutation rate could be even higher...
> Anyway, I left the possibility to anyone to fill in a different mutation
> rate for each marker.
>
> Wim
>
>

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