Archiver > GENEALOGY-DNA > 2009-12 > 1260747292

From: "Ken Nordtvedt" <>
Subject: Re: [DNA] R-U152 and R-L21 on the European Continent
Date: Sun, 13 Dec 2009 16:34:52 -0700
References: <>

For some reason you did not include the w(i) factors.

----- Original Message -----
From: "Tim Janzen" <>
To: <>
Sent: Sunday, December 13, 2009 4:14 PM
Subject: Re: [DNA] R-U152 and R-L21 on the European Continent

> Dear Ken,
> Thanks for your response. As I recall, I am using the 95%
> confidence interval formula that you recommended in May 2008 when we were
> initially developing these programs. See your message below. You are
> more
> of an expert on statistics than I am. I would be happy to send you a copy
> of my current program and you can take a look at how the confidence
> intervals are generated. The basic formula I using for the 95% confidence
> interval in generations is this: 2*G/SQRT(2*G*sum of the mutation rates).
> Sincerely,
> Tim
> From: Ken Nordtvedt [mailto:]
> Sent: Friday, May 23, 2008 6:56 PM
> To: Tim Janzen
> Subject: Re: using weighted mutation rates for calculating ages of
> subclades
> I believe the 95 percent confidence interval due to statistics will be
> plus
> or minus SquareRoot (2/G Sum w(i) m(i)) for deltaG/G
> For the S28/S21 MRCA that's plus or minus 50 percent
> So it costs to weight the markers.
> It does not buy you anything to use large sample size for the interclade
> MRCA age estimate. All pairs of haplotypes are basically sharing the same
> branch line with each other. Sample size is to get a diverse
> characterization of the clades as a whole so you are not taking the sum of
> mutations between odd-ball outliers of either clade.
> See my revised version of Generations2. I installed my own iteration
> lines
> of code. There is an instructional comments box to the right of the upper
> output cells
> -----Original Message-----
> From:
> [mailto:] On Behalf Of Ken Nordtvedt
> Sent: Sunday, December 13, 2009 1:45 PM
> To:
> Subject: Re: [DNA] R-U152 and R-L21 on the European Continent
> I don't know what statistical confidence intervals you are using, but they
> seem much narrower than I believe should be the case.
> For a simple TMRCA for two haplotypes, equivalent more or less to a very
> deep interclade TMRCA, the one-sigma G estimate variance stated in
> fractional units of the age, itself, is:
> <dG^2> / G^2 = 1 / {2G Sum i [m(i)/(1+4m(i)G)]
> with i being sum over markers.
> The above is of course for markers assumed to be the simple text book
> markers.
> My rough estimate using your 24 slowest markers is that for 30,000 year
> TMRCAs the one sigma dG/G is .36,
> while for the extremely old age TMRCA only gets as good as .29
> 95 percent confidence interval is close to twice the one sigma values.
> Ken
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