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Archiver > GENEALOGY-DNA > 2003-11 > 1069799356


From:
Subject: Re: [DNA] Measuring Genetic Distances [DYS464]
Date: Tue, 25 Nov 2003 17:29:16 EST


In a message dated 11/25/03 1:45:52 PM Pacific Standard Time,
writes:

> The IAM model scores
> all three of these as 23 matches and 2 mismatches, while the stepwise model
> weights the actaul number of steps off when considering the time to MRCA.

Sorry, I just sent out an empty message in the course of searching for an
example. I more-or-less understand the general principle, but I'm not sure it's
being handled in the best way for DYS464a-d. The fact that we don't know the
actual value for each physical marker confounds things. For example, take these
values:

15 16 18 18
13 15 16 16

If you compare a to a, b to b, c to c, and d to d, the Genetic Distance would
be 2 + 1 + 2 + 2 = 7. The FTDNA "Genetic Distance" report for the DYS464a-d
portion amounted to just 2, because both results have a 15 and a 16 in common,
but no matches on the remaining two markers. I think that must be a gross
underestimate of the "real" Genetic Distance.

Ann Turner - GENEALOGY-DNA List Administrator
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