GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2003-06 > 1057034291


From: Steve Williamson <>
Subject: Re: [DNA] Ancestry test - a must-read article URL
Date: Mon, 30 Jun 2003 21:38:24 -0700 (PDT)
In-Reply-To: <5531-3F010852-1617@storefull-2173.public.lawson.webtv.net>


Ray,
I need not? Anyway, John's explanation sounds a bit different from that of the User Manual, but I'll admit that could be my ignorance of statistics (I got a "C" in that in college). I guess I was tending to take at face value the assertion that the other possible values were many times less likely. I want to give the company the benefit of the doubt that they're not intentionally misleading us. That's really bad business practice if they are, because it will come out, and I think it would be the end of such tests.

Maybe my post to John sounded flippant, but I was serious about posting the calculations at a permanent URL - why not?

I have to admit, I don't think I would advise anyone at this point to spend their money on this test (I held an opposite view just a month ago).

Steve W.

Raymond Whritenour <> wrote:
Steve:

I hope John Chandler will answer you, and I'm sure he will; however, you
need not understand any more than what DNAPrint genomics, Inc. says,
themselves, about the accuracy of their 2.0 BGA test. On the very last
page of the User Manual, in the FAQ section, they explain "Error in the
test." The important quotation, here, is this:

"...as we have also explained, there is a second type of error called
statistical error, and the contours in your triangle plot show the
boundaries of statistical confidence."

Look at anybody's triangle plot, who has an MLE showing minor NA
ancestry, and at least two of the confidence contours run from 0% NA to
as much as 40% NA. Most have many points which plot below 0%. And, as
DNAPrint tells us, any one of these points is your possible true value.
With this kind of a spread, what possible use can such a test have for
genealogy? In most cases, there are so many points which plot "below"
0% that one of those points is MORE LIKELY to be your true percentage
than your MLE!

Ray Whritenour


==============================
To join Ancestry.com and access our 1.2 billion online genealogy records, go to:
http://www.ancestry.com/rd/redir.asp?targetid=571&sourceid=1237



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