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  • Disappearing Big-Y matches

    Hi All,

    Since I received my Big-Y700 results on July 11 I have not only not heard of any new Big-Y matches but also lost more than 12 long standing matches. These matches were positive for my Z17611 Terminal haplogroup and so either they, or I, have since July had our Z17611+ result amended ???

    Has anyone else encountered this issue.

    George

  • #2
    I just noticed my matches also went down - now just 1 - used to be several (6-7?)

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    • #3
      What is your terminal haplogroup ?

      Did you loose your matches shortly after you BG700 results came back ?

      I think this means any new Big-Y 500 or 700 matches won't find me, or us, as a match. I would suggest folk do a screen grab of the Block Tree and Matches List from their Big-Y Results pages before their matches get deleted.

      Comment


      • #4
        Good Idea George, The reason this is happening is because of FTDNA's matching program of a limit of 30 mismatched SNPs. The Big Y-700 test finds a lot more SNPs and Not-Named variants, so therefore goes over the 30 limit. FTDNA needs to completely rewrite the Big-Y matching program. I have emailed FTDNA several times and they just ignore me.

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        • #5
          I can understand there might be an issue with their algorithm but they should have advised us of the problem. Like you I asked the helpdesk and was simply told they know there is an issue that they are working on. I would expect them to tell us customers before we suffer the consequences. I am assuming any new Big-Y700 matches that I should be informed of simply will not appear. I have not seen any new matches since before my Big-Y700 results came back. Here is my Z17611 haplotree.
          Can you explain how my 2 matches, on the left, survive the 30 mismatched SNPs limit. Sorry about the size of the pic, hope you can read it. Final question - why is it impossible to temporarily increasng the 30 limit ?
          My-disappearing-matches.jpg
          Last edited by George Jamieson; 8th August 2019, 03:38 PM.

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          • #6
            Originally posted by George Jamieson View Post
            I can understand there might be an issue with their algorithm but they should have advised us of the problem. Like you I asked the helpdesk and was simply told they know there is an issue that they are working on. I would expect them to tell us customers before we suffer the consequences. I am assuming any new Big-Y700 matches that I should be informed of simply will not appear. I have not seen any new matches since before my Big-Y700 results came back. Here is my Z17611 haplotree.
            Can you explain how my 2 matches, on the left, survive the 30 mismatched SNPs limit. Sorry about the size of the pic, hope you can read it. Final question - why is it impossible to temporarily increasng the 30 limit ?
            My-disappearing-matches.jpg
            I can not see how many SNPs that define the sub-clade and most importantly the number of Not-Named SNPs, but I have been through this several times with FTDNA. I gave them a very detailed list of all my SNPs and Not-Named SNPs and proved that they were under 30 and that the reason for the mismatch was because they were including bogus SNPs that should not be included. They ignored me. Now with the new Big Y-700 there is a lot of new SNPs and Not-Named SNPs that push you over the 30 limit. FTDNA updated their Phylogenetic tree last night and I went from 13 to 2 Not-Named SNPs. (They named them) So you might get some of your matches back. But thats beside the point that FTDNA needs to completely rewrite their Big-Y program. I just gave up and send my members to YFull where they get their true matches plus more.

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            • #7
              I've not got any further forward on this. I think we need to ask FTDNA to clearly define what a match actually is. It is obvious that matches are no longer based on a common haplogroup. I have also stopped recommending Big-Y to my projects.

              If, for example, I have 31 single subclades between me and my 31x GrtGrdFather or a cousin 6 times removed (I think these roughly equate to the 30 variants and 5 branch limit. I am not sure as I can not work out how FTDNA apply their rules) then I should not consider them part of my family tree.

              Ericjle, just in case you are interested the missing figure is 18 variants.

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              • #8
                Absolutely, we need a clear statement from FTDNA on what they mean by a Big Y match!

                Comment


                • #9
                  This is FTDNA's statement on
                  BigY- Results - Matching
                  The Matching tab displays your terminal SNP matches. Your terminal SNP determines the terminal (final) subbranch (on the Y-DNA haplotree) to which you belong.

                  A person is considered a match if they have 30 or fewer differences in SNPs with you, and their haplogroup is downstream from your haplogroup or downstream from your four closest parent haplogroups.


                  Am I wrong to advise my project members that any Terminal Haplogroup assignment is a TEMPORARY assignment until remaining Private Variants find a match. It is a temporary assignment and not their FINAL Terminal Haplogroup.

                  Can someone at FTDNA please explain why these limits are being applied.
                  What value do they add to our research.
                  Is there any plans to change them ?

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