I have also not been overly impressed with Ancestry.com's phasing, particularly with their lowest confidence matches. I did an analysis on this topic in August. See http://archiver.rootsweb.ancestry.com/th/read/AUTOSOMAL-DNA/2013-08/13765547 77 for background. I found that about 59% of my lowest confidence matches did not appear in the match lists for either of my parents. However, for the moderate confidence and higher level matches, less than 10% of my matches did not appear in the match lists for either of my parents. I think it is reasonable for people who have tested at Ancestry.com to encourage their matches that Ancestry.com who are listed as moderate confidence or higher to transfer their data to GEDmatch so that you can review the matching HIR data there. It is clear that the optimum phasing is done with two-parent/one-child trios and data from other close relatives. Phasing using population data should be used only after all the phasing using close relatives has already been completed. Sincerely, Tim Janzen -----Original Message----- From: autosomal-dna-bounces@rootsweb.com [mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of Jim Bartlett Sent: Thursday, November 21, 2013 5:17 AM To: autosomal-dna@rootsweb.com Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing Barbara As I understand it, they look at your DNA data in general and select some other persons data (called a reference sample) who might be a stand in for your parents and phase your data. The theory, as I get it, is that this pseudo-phasing is better than nothing and helps segregate out some IBS matches. I've looked at a lot of Ancestry matches who have uploaded to GEDmatch and match me there. I've tried to Triangulate them when several fall on overlapping segments - both among the Ancestry kits, and with kits from the other companies. Although a few do Triangulate (indicating IBD segments); a lot do not. Many (most) of my Ancestry matches at GEDmatch are in the bottom third of my list of matches there, with small segments which usually turn out to be IBS - I quit using them - even with Jeff's tool, I was usually unsuccessful in finding the Ancestry kits at GEDmatch who matched me, back on my Ancestry list. To say the least - I was not impressed with what they called phasing. Jim - Sent from my iPhone - FaceTime!