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    Hey all, so just got my results through, I have 370 pages of matches haha (But I am Jewish so that's no surprise!)

    I was wondering if anyone can help (in very simple terms) to sort the wheat from the chaff so to speak!?

    So one known cousin I match with at 2nd-3rd Cousin level the figures are 267.51 shared cM and longest block 49.76 we have a paper trail so know we are 3rd cousins through our great grandfathers.

    But after that its all a blur

    For example, I have another 2nd-3rd cousin which is shared 165.56 cM and longest block 16.44. Those figures are much lower than the first match but the match is in the same relationship range?

    Help please!

  • #2
    Oh it also says with the second match above that I am an x-match?

    Comment


    • #3
      Longest Block tells you about the quality of the guess.

      As they say, individual results might vary. The Longest Block longer than 20 should make you look really hard into the paper trail. With the other matches, it is not that there is no chance of being related, it is that likelihood of relationship is getting decreasingly smaller as the longest block gets smaller. Some people found that 15 was their magic number.

      My entire post is about the Longest Block only.

      There are interviews in FTDNA Learning Center, where people share their experiences. For example, Eugen Hartmann – Genetic Genealogy Interview from April 2014.

      Comment


      • #4
        Thanks for the reply.

        So I have 41 matches were the longest block ranges from 20 to 34.75 (I have excluded the longest block of 49.76 as this is a known cousin so no mystery there)

        Within these >20 longest blocks I have a range of 2nd - 3rd cousins to 5th - remote

        Comment


        • #5
          Originally posted by Seth_Rogoff View Post
          Thanks for the reply.

          So I have 41 matches were the longest block ranges from 20 to 34.75 (I have excluded the longest block of 49.76 as this is a known cousin so no mystery there)

          Within these >20 longest blocks I have a range of 2nd - 3rd cousins to 5th - remote
          Only 41 matches in that category? If you sort your results by length of longest block, what is the shortest longest block you see?

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          • #6
            Do you mean sorting with every match I have? (I have 3,701 matches)

            If I do it on the complete list my shortest block, at the end of page 370 is 7.10
            Last edited by Seth_Rogoff; 7 October 2014, 07:56 AM. Reason: spelling

            Comment


            • #7
              Originally posted by Seth_Rogoff View Post
              Do you mean sorting with every match I have? (I have 3,701 matches)

              If I do it on the complete list my shortest block, at the end of page 370 is 7.10
              Yes, that's what I said, but not what I meant (sigh). I just happen to have the number 20 cM on my brain, because FTDNA seems to require 20 cM total before declaring a match. There are reports that this requirement interferes with finding legitimate matches.

              Nevertheless, there was some interest in your reply. The typical shortest longest block seems to run in the 7.7 cM range.

              Comment


              • #8
                Seth,

                I'm Jewish and I have results similar to yours. I have found one previously unknown 3rd cousin, who has a longest match of about 29 CM. When I saw the match I realized that his name and the names of his ancestors looked vaguely familiar. I contacted him to ask about his grandparents and I was then able to find enough documentary evidence to conclude that our great grandfathers were brothers. Previously I did not know about that branch of the tree but once I knew where to look the evidence fell into place.

                All I can suggest is that you focus on the close matches and look at the names and locations of ancestors. It also helps if you have more of your relatives tested.

                Comment


                • #9
                  Thanks for the replys

                  So I'm still trying to understand what is more important? Longest block or shared cM?

                  So I have on match the FTDNA say is 2nd-3rd cousin but longest block is only 16.44 but shared cM is 165.56.

                  But another match that is longest block 34.75 is 4th cousin to remote? (Shared cM is 72.55)

                  Thanks all

                  Comment


                  • #10
                    Originally posted by creback View Post
                    [----] All I can suggest is that you focus on the close matches and look at the names and locations of ancestors. It also helps if you have more of your relatives tested.
                    The second advice is a very good one.

                    I am in a partial disagreement with the first comment, though. In my opinion, you should concentrate first on those matches with whom your Longest Block is longer than 20. Predicted relationship (whatever that relationship or relationship range is) to any of these 41 people is most likely correct. Most likely correct does not mean that it is certain! Thus you have a hint how far back to look for a common ancestor. Remember that, due to a possible generation gap, a person your age could be your cousin twice removed or you could be their cousin twice removed; so in such a case you might need to go back additional two generations.

                    I am not saying ignore thousands of other matches, but work in the order of the Longest Block. So after you dealt with the first 40+ of matches, go to the matches in 15-20 range etc.

                    Warning: each week you will be getting new matches

                    P.S. Of course you could go in the order: cousins, 2nd cousins, 3rd cousins, 4th cousins etc., but considering how many matches you have that would not be optimal (thus I am not recommending it). Additionally, expanding/growing your tree would make it easier to deal with the matches. Just chasing somebody who might or might not be in your tree would not allow you to expand your tree.
                    Last edited by dna; 7 October 2014, 12:10 PM.

                    Comment


                    • #11
                      Originally posted by Seth_Rogoff View Post
                      Thanks for the replys

                      So I'm still trying to understand what is more important? Longest block or shared cM?

                      So I have on match the FTDNA say is 2nd-3rd cousin but longest block is only 16.44 but shared cM is 165.56.

                      But another match that is longest block 34.75 is 4th cousin to remote? (Shared cM is 72.55)

                      Thanks all
                      cM and LB refer to two different aspects:
                      * relationship predicted = cM (it is a little bit more complex than that)
                      * how reliable that prediction is = LB (unfortunately it cannot be directly translated into a percentage from 100% (long blocks) to 0% (very short long blocks).

                      Comment


                      • #12
                        Thanks for the message so I understand a little better now, the longer the longest block then the more reliable that the match its.

                        So if I've got two matches with the same amount of shared cM, say 150 cM, if ones longest block is 30 and the others is 15' then the match with a LB of 30 should be looked at first and could possibly be a 'closer' relation?(less generational distance?)

                        Comment


                        • #13
                          Good Question

                          Originally posted by Seth_Rogoff View Post
                          Thanks for the replys

                          So I'm still trying to understand what is more important? Longest block or shared cM?

                          So I have on match the FTDNA say is 2nd-3rd cousin but longest block is only 16.44 but shared cM is 165.56.

                          But another match that is longest block 34.75 is 4th cousin to remote? (Shared cM is 72.55)

                          Thanks all
                          Serth,
                          I'm sure glad you asked this question. I have not been able to figure this out either. Using FTDNA's default Longest Block search I have an unknown to me person with a Longest Block of 31.36 and Shared cM 51.12 showing up as my closest match. My first Known Relationship is my Paternal 2nd cousin once removed who doesn't show up until page 2 of my results with a Longest Block of 21.79 and Shared cM 109.41. I think I understand this a bit better after reading the answers to your questions.
                          Thanks everyone,
                          Hoppy

                          Comment


                          • #14
                            Originally posted by Seth_Rogoff View Post
                            Thanks for the message so I understand a little better now, the longer the longest block then the more reliable that the match its.
                            I'm glad I was able to help.

                            Originally posted by Seth_Rogoff View Post
                            So if I've got two matches with the same amount of shared cM, say 150 cM, if ones longest block is 30 and the others is 15' then the match with a LB of 30 should be looked at first and could possibly be a 'closer' relation?(less generational distance?)
                            No

                            Let me exaggerate a little. The one with LB of 30 would only have 20% chance that yours and his DNA are matching by a pure random chance. The one with LB of 15 would have over 95% chance that yours and hers DNA are matching by a purely random chance.

                            Comment


                            • #15
                              Originally posted by dna View Post
                              I'm glad I was able to help.

                              No

                              Let me exaggerate a little. The one with LB of 30 would only have 20% chance that yours and his DNA are matching by a pure random chance. The one with LB of 15 would have over 95% chance that yours and hers DNA are matching by a purely random chance.
                              I think my brain is going to explode!!

                              Comment

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