GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2003-09 > 1062477755
From: David Faux <>
Subject: Re: [DNA] Cecelia's Mother's DNAPrint 2.0 Results - a big surprise
Date: Mon, 1 Sep 2003 21:42:44 -0700 (PDT)
A reply to my own reply:
While we are on the subject, and my mind has turned in this direction, it reminds me of the discussions I had with Charles Kerchner some time back about other potential "problems" with the test - that mean that we cannot meaningfully compare, for example, a test result done myself (in 2001) with a sibling (in 2003). The problem: the test may have been using algorithm X in the first case but Y in the latter (as explained below). In addition, it appears that they have from time to time changed the number of markers used, and dropped some completely while adding others - with unknown or unpredictable results. The distinctly different data from Cecelia's two tests of her DNA strongly suggest that there has been some test tweaking.
Test revisions (improvements?) are laudable, but not without knowing that the test done on myself, my mother, and my uncle were in effect three different tests - so direct comparisons cannot be made.
David Faux <> wrote:
If you are correct - and curiously I made a statement about their algorithm being potentially terribly flawed in a post sent about the same time as yours - then this is truly disturbing. I am running a whole series of tests on descendants of each of the 4 children of my documented Native American ancestor. Should you perchance be correct (and I fear you may be) then I will be comparing apples to oranges, and my results (which I planned to include in a 3500 name book on the Young family) are potentially worthless and perhaps meaningless.
Considering the number of individuals on this List who have reported minority Native American, but have not a shred of documentation to support the finding (plus a genealogy that made the findings very unlikely) I am beginning to wonder whether the algorithm was "amended" at some point to give the customer what they want - a little bit of Native American. Now the algorithm would not work 100% of the time to effect this purpose, so there would be some individuals who might even come up 100% Indo European - these results basically being a false negative - however playing the numbers game it would give they and their customer's what they want more times than not.
Another hypothesis is that they were well aware that they were getting Native American signals where they should not be and have altered the algorithm to address this matter. Tweaking the algorithm is fine as long as the customer is informed of the change and the rationale behind this move. In addition it should be done in conjunction with the data from people such as myself with a fully documented genealogy. Here, in testing 10 members of my family (and others in the same boat), if the algorithm is on the money, then the results should follow the laws of genetics. Otherwise this is a very shabby move and I think that it is time I brought my project to a halt until the DNAPrint people can explain what the heck they are doing behind the scenes.
There has often been a veil of secrecy involving this test which has led to much speculation and few hard facts. When time permits I will thrash out the matter with Tony and Matt at Ancestry by DNA but at the moment am too preoccupied with other matters. Perhaps someone would like to grill them a bit on whether there have been changes to the algorithm (and how many times this has occurred); and what we can expect from the 2.5 / 3.0 version (very little more than we have I fear since I have not heard that they have been doing extensive testing of representative samples from around the world - hope I am misinformed).
Dr. David K. Faux, P.O. Box 192, Seal Beach, CA, 90740, USA
|Re: [DNA] Cecelia's Mother's DNAPrint 2.0 Results - a big surprise by David Faux <>|