GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2010-03 > 1267811017


From: Al Aburto <>
Subject: Re: [DNA] TMRCA Confidence Intervals
Date: Fri, 05 Mar 2010 09:44:01 -0800
References: <00a201cabc89$5bcc7d70$5e82af48@Ken1>
In-Reply-To: <00a201cabc89$5bcc7d70$5e82af48@Ken1>


Bravo Ken!
Al

> On 3/5/2010 9:29 AM, Ken Nordtvedt wrote:
> A couple days ago I reported finding a relationship between the sigma (statistical confidence interval) for variance-based TMRCA age estimates of individual clades and the difference between the TMRCA and coalescence age estimates. This eliminates the unknown tree-dependent factor from the issue. The relationship is:
>
> SigmaG = SquareRoot { [ G - G* ] / M }
>
> G = Sum i [ r(i) - rf ]^2 / NM is TMRCA when summed over STRs
> G* = Sum i [ r(i) -<r> ]^2 / NM is coalescence age when summed over STRs
> M is sum of STR mutation rates
> rf is founder's assumed STR repeat value
> <r> is arithmetical average of STR repeat value
>
> For clades in the 3000 to 4000 years age area, the 2SigmaG values seem to be running about 20 to 22 percent of the G age estimates.
>
> I am modifying my Generations4 excel spreadsheet to add G estimate to the already present G* estimate for clades, so that SigmaG can be estimated.
> It will come out as Generations5.
>
> The SigmaG* is being worked on.
>


This thread: