GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2005-07 > 1120254434


From: John S Walden <>
Subject: Re: [DNA] mtDNA results - Helena
Date: Fri, 1 Jul 2005 17:47:14 -0400
References: <dd.29357684.2ff5f585@aol.com> <fef9eee40507010830292c0ff0@mail.gmail.com> <REME20050701141217@alum.mit.edu> <fef9eee4050701120178bb303b@mail.gmail.com> <REME20050701162656@alum.mit.edu>
In-Reply-To: <REME20050701162656@alum.mit.edu>


On 7/1/05, John Chandler <> wrote:
>
> John wrote:
> If the mutation rate is m, the number of markers is n, and the number
> of generations is g, then the cumulative probability that one mutation
> will be found for any number of generations from 0 to g is:
>
> 1 - (1-m)^(ng) - (1 - (1-m)^N) g (1-m)^(n(g-1))
>
> (counting both ways). That gives about 350 generations one-way for
> the 2.5th percentile point if m=3e-7.



OK I got that one working on my excel spread sheet and I do get the 2.5%point
at 350 times 2 generations

An you agreed that the odds of 75 to 1 [0.0134 or 1.35%] was about right for
the
poisson solution to 1143 markers
a rate of 3E-7 and One mutation at 2 times 20 generations.

Now when I look at the Cumulative Probablity from the above equation
[when I have assumed that N=n]
Again at 2*20 = 40 generations I get a value of 9.1E-5 [or 0.00009]

I would think the two numbers should be a bit closer than 0.0134 and 0.00009

What is wrong with my thinking that these should be closer?

John W

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