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Archiver > GENEALOGY-DNA > 2003-09 > 1062695620
From:
Subject: Re: From Tony Frudakis RE: [DNA] Cecelia's Mother's DNAPrint 2.0 Results
Date: Thu, 4 Sep 2003 13:13:40 EDT
In a message dated 09/02/03 5:37:56 PM Pacific Daylight Time,
writes:
> Tony wrote:
>
> >Comparing a 30 marker test result with a 71 marker test for another person
> >is just as reliable (or unreliable, depending on how you look at it) as
> >comparing 71 marker test results for two separate people - both the 30 and
> >71 marker tests involve a few percentage points of error on average
>
> Again, we have the odd use of the word "error" with different meanings
> to different people. Customers expect it to mean the total
> uncertainty of the reported values, but Tony apparently uses it to
> refer to just the portion of uncertainty due to possible laboratory
> measurement error (which happens to be a small part of the total
> uncertainty). Suffice it to say that the statistical uncertainty
> ranges from about 8% (for African) to 15% (for Amerindian and Asian).
> In short, the total uncertainty is never just a "few percentage
> points".
I interpret it still another way -- that the MLE would only change a few
percentage points if you compared a 30 marker test with a 71 marker test, or a 71
marker test with a handful of FL (failed) results, or a 71 marker test with a
completely different set of markers. The genotyping error does appear to be
very small.
> >As for how we are testing, right now we are relying on mathematical
> >simulations rather than large international collection efforts, because the
> >former is much tighter and easier to control variables for (which is
> crucial
> >for a sound study).
>
> This is perhaps the most disturbing news of all. There shouldn't be
> any variables in the algorithm except the allele frequencies for the
> target populations. These frequencies can't be "controlled" -- they
> must be measured.
I agree that more raw data would be highly desirable, but I can see it would
also be enormously expensive to discover new Ancestry Informative Markers in
good reference populations, or even to broaden the populations tested for the
current AIMs. I bet lots of newly discovered SNPs will not be AIMs -- they will
either be too private or too cosmopolitan to be useful. It's also going to be
harder and harder to find current day populations without admixtures.
Ann Turner - GENEALOGY-DNA List Administrator
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