Z17911 BigY
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There are really four levels of reporting for each SNP: positive,
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negative, maybe, and no coverage. The 'maybe' results (this is my terminology, not FTDNA's) are markers where you show the SNP in your raw results, but it was in a questionable read area of the test. This means you probably have the SNP, but FTDNA takes a very conservative approach and does not report these. If additional people on your branch get 'maybe' results for that same SNP, the more likely it is a valid SNP for that haplogroup. A positive test for that SNP verifies it as a good one and (usually) establishes it on the tree. No coverage means the test didn't read in this area, so you can't really know from that test alone. If you do, however, test positive for a downstream SNP, then you'll know you also have all upstream SNPs, even if your test results show 'maybe' or no coverage results for them. My tree and FTDNA's tree has Merrick two branches downstream (BY11573 and a terminal SNP of BY11565), from you and I who are at Z17911. So this is the 2 SNP differences. But Thomas and Bennett also have BY11573, so this means they should show a 1 SNP difference to you, right? The answer would be yes, except that Merrick, Thomas, and Bennett all were 'maybe' results for BY11573, so FTDNA doesn't count these. You'll see that Thomas and Bennett still show terminal SNP at FTDNA of Z17911, not BY11573. So why does Merrick get credit for BY11573 when his 'maybe' result is the same as Thomas and Bennett? Because we know BY11573 is a valid SNP because of Goff's positive result for it. This established its definitive location on the tree. While Thomas and Bennett don't get credit for it because of their 'maybe' results (they show 0 SNP differences to you), Merrick does because his terminal SNP is downstream from it. He can't NOT have it, even though his results were 'maybe'. This highlights how valuable Goff's SNP pack results were to our part of the tree. They really verified two more haplogroups - BY11573 (the first positive result after three 'maybe' results) and BY11565 (the second positive result with Merrick). Hopefully that helps. Jared On Thu, Feb 2, 2017 at 7:16 AM, Joel Hartley <joel@...> wrote:
Does anyone know why I have a 0 SNP difference to Thomas and Bennett and a 2 |
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To add a some additional thoughts on this...
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- You can see the four SNP test result states in Alex's mutations matrix at the Big Tree. - How do we know Thomas and Bennett are BY11573 if their results are 'maybe'? Because it would be incredibly unlikely that it's mere chance that they both show this particular mutation at this exact location that also aligns with a proven SNP. FTDNA, however, is super conservative about making such assumptions. - While FTDNA does not report 'maybe' results for Big-Y, it does for SNP Packs. It shows these with an asterisk and describes them as "no calls". My SNP results show BY4028*, for example. Even though this SNP was a 'maybe' test result, because my terminal SNP is downstream from it, I know I have it. - FTDNA uses some unknown formula or method to sometimes define 'solo' terminal SNPs - when only one person has tested positive for it. For example, Pillsbury shows terminal SNP of BY13850 even though he's the only one to have ever tested positive for it. Hays (N28178) similarly is alone with BY13845. On the other hand, Joel Hartley shows terminal SNP of Z17911, even though he alone has the A11130 SNP. I'm not sure how they determine which solo SNPs are worthy of 'terminal' status. I generally use FTDNA's determination in marking the haplogroups of my tree - - as verified or theoretical. - Remember the term "terminal SNP" is a misnomer - it really means "temporary terminal SNP" - it's the last one we can reasonably verify... for now. Jared On Thu, Feb 2, 2017 at 7:25 PM, Jared Smith <jared@...> wrote:
There are really four levels of reporting for each SNP: positive, |
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Then scratch what I posted before - though this is the logic used for
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positioning on the tree. I recall now that I had written earlier about these 2 SNPs. These are both known SNPs, but for totally different haplogroups. They are in poor coverage regions on your tests, so I think they are either misreads or they are private SNPs that just happen to coincide with the other known SNPs. It seems FTDNA has identified them as differences for you because they were in some database somewhere at the time the results were processed. CTS3563 is an SNP for the E haplogroup (search for CTS3563 at ). Alex has it highlighted pink on Merrick's results which means it's on the edge of a coverage region. CTS11841 is very similar. This is C>T at position 23311208. This is an I haplogroup SNP in the ISOGG list. This is one that you have that Merrick doesn't. This mutation isn't listed by Alex for you, probably because it is on the very edge of a coverage region - so probably a misread for you. CTS11841 should also show as a difference between you and Bennett (he's negative for it). But it is a 'maybe' for some of the others on our branch (Thomas, one of the Hays men, etc.). This reinforces that it's in a poor read area. I suspect that FTDNA dropped this one from consideration between the time your results were processed and Bennett's were, so that's why it's not showing for you two... or something. This is what differentiates Alex's analysis from FTDNA's tools - Alex takes the time to analyze these things to weed out such anomalies and questionable reads, and he look for possibilities (especially between multiple men) that don't fit within FTDNA's automated processes. Rumor has it some new SNP tools will be coming to FTDNA soon - their current tools seem to be rather lacking. Jared On Fri, Feb 3, 2017 at 4:46 AM, Joel Hartley <joel@...> wrote:
Here are the two SNPs that the Big Y shows as being different between me and |
Jared Smith