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Archiver > GENEALOGY-DNA > 2005-07 > 1120244501


From: John S Walden <>
Subject: Re: [DNA] mtDNA results - Helena
Date: Fri, 1 Jul 2005 15:01:41 -0400
References: <dd.29357684.2ff5f585@aol.com> <fef9eee40507010830292c0ff0@mail.gmail.com> <REME20050701141217@alum.mit.edu>
In-Reply-To: <REME20050701141217@alum.mit.edu>


On 7/1/05, John Chandler <> wrote:
>
> The 95% confidence interval for the TMRCA is the
> interval such that the probability is 5% that the time lies outside
> the interval for the given number of mutations. Taking the number
> of markers to be 1143 and the mutation rate to be 1e-6, I get a 95%
> confidence interval of about 3000 years ago to 70,000 years ago for
> one mutation.
>
> I am having trouble getting this one
My thinking was that the 95% interval is on each side of the most likley
point.
So this 100% interval should be made up of 3 parts
2.5% in the near term where is not enough time has elapsed for even one
mutation to happen
This is followed by many years for the 95% part.
And finally in the distant past there is the 2.5% part where so much time
has passed that there will be more (maybe many more ) than just one
mutation.

RE I get a 95% confidence interval of about 3000
So with a mutation rate of 3 times faster than the one I used
[were the estimate of 3E-7 is larger than ones used in the phyloginetic tree
construction]
Your 95% interval is three times further out in time than I calulated.

So if you used 0.3E-06 what whould that
near term point of the inverval be for the MRCA for one mutation
[remider the number of births doubles from MRCA to present as we have two
lines comming from the MRCA of X years ago.]

John W

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