Hi everyone, I hope we can find some consensus here and maybe some of you know even what number (of matches at a certain loci) is used by AncestryDNA to identify pileups. We're obviously not talking about 1000 here as that would give us 499500 1-to-1 comparisons to run between the 1000 matches. That's the main reason why DTC DNA testing companies (and also GEDmatch) are interested to identify pileups to limit useless calculations (which in the end will still not find a single triangulated group (maybe) or it's too far back anyway, see the Timber algorithm used by AncestrDNA to cut matches. a) I have 97 matches (at the same loci) for one of my kits (at the "X" chromosome interestingly, it's a female person), which means 4656 combinations. Is that number already a pileup? How about: b) 52 matches = 1326 combinations c) 36 matches = 630 combinations d) 23 matches = 253 combinations e) 18 matches = 153 combinations Where is the line to draw? At a, b, c, d, e or where? What is the largest number of matches that you have in your triangulated groups? We obviously don't want to miss out a large TG as it also means a lot of people can "crowdsource" together and identify the CA much quicker than a group of 3 can (usually means also more family trees to compare with). Thanks for your answers! Andreas (WEST) born BASSO My ancestors: [http://www.wikitree.com/genealogy/Basso-Family- Tree-23](http://www.wikitree.com/genealogy/Basso-Family-Tree-23)

Hello Andreas > What is the largest number of matches that you have in your triangulated > groups? My largest group is 67 people matching me (and my mother) on chromosome 8 within the area between 109000000 - 128000000. I would have done some cross checking when each of them initially shared with me and most of them I have marked as cross matching, although not everyone matches everyone else. I have just rechecked two of them - one matches 62 of the group (this person matches me from 109000000 - 126000000, 16.8cM), the other 50 (they match me from 117000000 - 125000000, 10cM). Even the person with the smallest match to me in this area (118000000-123000000, 5.3cM) matches 34 of the others, his longest match to any of them being 15.5cM, over a segment 103000000 - 123000000. I wish it were true that the large groups of 'people can "crowdsource" together and identify the CA much quicker than a group of 3 can ' . That had been my hope but, in most of my larger TGs, the majority of the people match each other over just one segment and so all seem to be equally distant from each other. Whereas the first match I had, where we identified a common ancestor, was actually the only match on that segment. I suspect (as I am in the UK), that the larger TGs are where a distant ancestor emigrated (usually to the US) so long ago that they now have many descendants, who just happen to be DNA tested. As to whether such groups class as "pile ups", I don't know - but if you start discounting them as being too distant, what's the point of triangulation? Where is the boundary between a "relevant" TG and a "population based" TG? My working principle, for now, is that if people in the group cross match, then the group is genuine/relevant. Best wishes Barbara Griffiths On 13 December 2015 at 10:56, Andreas West via <genealogy-dna@rootsweb.com> wrote: > Hi everyone, > > I hope we can find some consensus here and maybe some of you know even what > number (of matches at a certain loci) is used by AncestryDNA to identify > pileups. > > We're obviously not talking about 1000 here as that would give us 499500 > 1-to-1 comparisons to run between the 1000 matches. That's the main reason why > DTC DNA testing companies (and also GEDmatch) are interested to identify > pileups to limit useless calculations (which in the end will still not find a > single triangulated group (maybe) or it's too far back anyway, see the Timber > algorithm used by AncestrDNA to cut matches. > > a) I have 97 matches (at the same loci) for one of my kits (at the "X" > chromosome interestingly, it's a female person), which means 4656 > combinations. Is that number already a pileup? > > How about: > > b) 52 matches = 1326 combinations > > c) 36 matches = 630 combinations > > d) 23 matches = 253 combinations > > e) 18 matches = 153 combinations > > Where is the line to draw? At a, b, c, d, e or where? > > > What is the largest number of matches that you have in your triangulated > groups? > > We obviously don't want to miss out a large TG as it also means a lot of > people can "crowdsource" together and identify the CA much quicker than a > group of 3 can (usually means also more family trees to compare with). > > Thanks for your answers! > > Andreas (WEST) born BASSO > > My ancestors: [http://www.wikitree.com/genealogy/Basso-Family- > Tree-23](http://www.wikitree.com/genealogy/Basso-Family-Tree-23) > > ------------------------------- > To unsubscribe from the list, please send an email to GENEALOGY-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message