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From: "Kenneth Nordtvedt" <>
Subject: Re: [DNA] Any feedback on the RCC method of TMRCA estimates?
Date: Mon, 7 Nov 2011 07:36:49 -0700
References: <mailman.1080.1320605197.10215.genealogy-dna@rootsweb.com><20111106152808.L0KW2.1830091.imail@fed1rmwml4201><CAP16=-fkGdURdDwYhJ5XHEkL20bejaMZg_gcRgSM23yKt5Togg@mail.gmail.com>
In-Reply-To: <CAP16=-fkGdURdDwYhJ5XHEkL20bejaMZg_gcRgSM23yKt5Togg@mail.gmail.com>


-----Original Message-----
From: Stephen Forrest
Using the Euclidean distance (what
mathematicians call the 2-norm) instead of the sum of pairwise differences
(the 1-norm) doesn't seem to be traditional for comparing STRs. but it at
least makes some physical sense.

[[GD is sum of absolute values of differences of str repeat values; Variance
is sum of squared differences of str repeat values. But for young times
back to common ancestor most of the repeat differences are -1 or +1 and
therefore contributions to GD and to Variance are the same. For larger
times Variance automatically takes into account back mutations and multiple
steps of mutation in the same direction; GD requires warping to relate to
time. This probably has something to do with 1-forms and 2-forms, but in
multiple dimensions I have always considered euclidean distance as square
root of sum of squares of coordinate differences. KN ]]

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