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Archiver > GENEALOGY-DNA > 2004-01 > 1073046138


From: (Raymond Whritenour)
Subject: [DNA] By George, I think I've got it! LOL
Date: Fri, 2 Jan 2004 07:22:18 -0500 (EST)


Debby:

Let's just say you're beginning to get it.

The yellow confidence contour on your triangle chart is NOT a band of
"least likely" possible values, though it does represent a "scientific
level of confidence." It's a line made up of points each of which is 10
times less likely to be your true value than your MLE. A confidence
interval of 100 times less likely, or 1,000 times less likely, or
whatever, could be added to the triangle chart, and any point on those
contours could possibly be your true value, rather than the MLE. Very
unlikely, but still possible.

Furthermore, it is just as likely that your true minor ancestry
percentage lies "somewhere" among any ten points on your yellow
confidence contour as at the point of your MLE. And, it is MORE likely
that your true value lies "somewhere" among any eleven or more points on
the yellow line than at your MLE. It is twice as likely that your true
value lies "somewhere" among any twenty points on the yellow contour
than at your MLE. So, in most cases, it is more likely that your true
minor ancestry lies "somewhere" among the possible values on the yellow
confidence interval which lie BELOW 0%, than at your MLE!

The 5% error is supposedly the maximum lab error. There is an as yet
undetermined systematic error rate (due to faulty sampling), which MUST
be quite high, since someone with no NA ancestry can be given a 10% NA
MLE and a gray (2 times less likely) confidence interval which never
drops to 0%.

I'm not a scientist, Debby, but I can see some of what's wrong with this
test. Pessimistic? You bet!

Ray Whritenour

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