GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2002-04 > 1019497260
From: "John F. Chandler" <>
Subject: Re: [DNA] Relative Genetics/Ancestry.com results
Date: Mon, 22 Apr 2002 13:41 EDT
In-Reply-To: firstname.lastname@example.org message <3CC44D1B.BCAA77E0@bellatlantic.net> of Mon, 22 Apr 2002 11:32:13 -0600
> While my Glennon family Y-DNA project is at FTDNA, I did get my personal
> sample tested by Rel.Gen./Ancestry just to make a comparison and to get
> some results on additional markers...
> All of the markers tested by both labs matched EXCEPT for DYS 388.
> FTDNA reported 12 on that marker and Rel.Gen./Ancestry reported a 13.
Any disagreement is disturbing, given that the RelGen numeric results
are now supposed to be calibrated properly. The only other post-cal
report of a comparison between FTDNA and RelGen showed complete
agreement. Hence, we know that somebody goofed somewhere. It might
be a good idea to recall the error rate published by Wilson et al. --
they tested many samples twice independently and compared the results
to obtain an estimated error rate of 0.7%.
> one thing that is worth pointing out under the heading of "Most
> Recent Common Ancestor" that raised some questions in my mind based on
> statistics that I have seen earlier. It is:
> # of Mismatches - 0
> Median Number of Generations - 3.6
> Possible Range in 95% Interval - 0.1 to 19.2
If this is based on 24 markers and a mutation rate of 0.2%, then the
median should be twice as much: 7.2 generations, with a 95% confidence
interval of 0.5 to 31.2 (I calculated that with a binomial distribution
by doing a continuous integral instead of a discrete sum, but the error
should be small). Perhaps they are assuming a mutation rate of 0.4%?
> # of Mismatches - 1
> Median Number of Generations - 8.9
> Possible Range in 95% Interval - 1.3 to 29.7
Again, too small. I get 17.5 median or (3.7 to 49.4). Again, this might
be the result of assuming a higher mutation rate. Then again, maybe
they took a table of results that was based on MRCA and thought it was
instead based on mutations between one ancestor and one descendant (and
so divided by two an extra time).
|Re: [DNA] Relative Genetics/Ancestry.com results by "John F. Chandler" <>|