GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2002-08 > 1030639143


From:
Subject: Re: [DNA] How Specific is 12 marker test
Date: Thu, 29 Aug 2002 12:39:03 EDT


In a message dated 08/28/02 11:14:59 AM Pacific Daylight Time,
writes:


> Matches----------------Matches out of 25--------------------Row
> out of 12____25__24__23__22__21__20 or fewer___Total
>
> __12_______60*_15___3___1___2_____9_________90
> __11_______na__15___5___3___1_____3_________27
> __10_______na__na___1___0___1_____2__________4
> 9 or fewer___na__na__na___0___2____31_________33
>
> Col .Total___60__30___9___4___6____45________154

This is an extremely useful exercise! Combining the results from different
projects gives a much clearer picture of the possible outcomes when upgrading
from a 12 to a 25 marker test. I guess the moral is to anticipate anything.
Some projects end up with more mutations than they want (thus breaking up
some matching sets), some end up with fewer mutations than they want (thus
being unable to discriminate between different branches), and some end up
with exactly the right number (everyone still belongs together, but branching
points become clearer).

This is a good-sized sample, but I was wondering if you'd be willing to
maintain this table and update it as more people upgrade? It would certainly
be too much to ask you to scan all the projects, but how about it people
notify you?

On the other hand, if Orin gets his matching database up and running, it
might be simpler to run queries on it. It would be interesting to analyze all
12/12 matches that arise from merging data from different projects. I bet the
outcome would be a much lower chance of matching on 25 markers than you found
within projects. Knowing that surnames are the same must change the "prior
probability" a lot, but we don't know how to quantify that.

http://nitro.biosci.arizona.edu/ftdna/models.html#Prior

Thanks so much for undertaking your analysis!

Ann Turner
GENEALOGY-DNA List Administrator
http://lists.rootsweb.com/index/other/Miscellaneous/GENEALOGY-DNA.html
DNA preservation kits: http://www.dnafiler.com


This thread: