I am using this blog to record my genealogy research progress. My research at this point is concentrated in Tennessee, Virginia, Kentucky and Pennsylvania records. Since many of my ancestors ended up in the Midwest and West my research sometimes takes me in that direction. I also research Irish records.
Friday, November 7, 2014
GEDmatch Segment Size May Be Different From That Reported by Your Testing Company
I found a long awaited match on our Owens line at Family Tree DNA yesterday. This person evidently transferred her results to Family Tree DNA immediately after this service was announced in October. I copied her email address and went to GEDmatch to see if she appeared in my Aunts results. I found her listed with two kits. I compared her two kits. Both kits showed identical results with my Aunt. Compared against my Aunt at GEDmatch I noticed their longest shared segment was 14.7. Her longest segment with my Aunt at Family Tree DNA was reported as 8.68?
A basically 6 cM difference. I've emailed this match to be sure we're comparing apples to apples. If there really is a 6 cM difference for the result on 19 (see their charts below) then there is a big problem somewhere?
Comparing results from Family Tree DNA, 23andMe, and GEDmatch there is a consistent 1 cM difference at GEDmatch with the occasional 3 cM difference. I checked to see if 23andMe was any closer to GEDmatch, but they also differ by 1 to 3 cMs (see above). I don't know how well 23andMe results compare with Family Tree DNA outside GEDmatch?
If we're using cM's to determine our relationship to a match and to triangulate it's important to have consistent numbers. Hope we can eventually compare with equivalent, agreed upon, standards. Right now I don't know whether I should accept the 14.7 result as correct or the 8.68 result? Or are we looking at different kits? Hoping to get answer soon?
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment