Louis Kessler’s Behold Blog The Behold User Forum
Blog Comments
192.
Triangulation does NOT mean IBD - Blog comment by lkessler - 4 Oct 2017
Debbie: Well, I'm just looking at the results. And FamilyTreeDNA seems to have many fewer disprovals of IBD by parents at any given cM level than AncestryDNA does.
193.
Triangulation does NOT mean IBD - Blog comment by debbiek - 4 Oct 2017
No I think it means the opposite. FTDNA can't use a higher threshold because they are not using phasing or any algorithms to remove pile-ups. The vast majority of matches that don't match either parent at AncestryDNA share under 9 cMs. Ancestry's own tests published in their white paper show that we would ...
194.
Triangulation does NOT mean IBD - Blog comment by lkessler - 3 Oct 2017
Very interesting, Debbie. So then it seems that FTDNA's criteria of at least one 9 cM segment is better (i.e. produces fewer false matches) than AncestryDNA's combination of phasing and inclusion of segments down to 6 cM. That may be indicative that AncestryDNA's phasing combined with its Timber may not be ...
195.
Triangulation does NOT mean IBD - Blog comment by debbiek - 3 Oct 2017
Louis, I shall look forward to your future blog post.
Inference is a popular word in population genetics and genetic genealogy. Unlike mathematics, we can't have complete certainty. It's therefore a question of testing hypotheses and quantifying the uncertainty. I've actually been very impressed by ...
196.
Deep Ancestors - Blog comment by jbissett - 3 Oct 2017
With all due respect, Steven Fox's VP spreadsheet works wonderfully, once the crossover points are correctly identified. Have you worked with it yet? As I said, your work can take the cousin matches back further than just the 4 grandparents, so some type of correlation between the two programs is definitely ...
197.
Deep Ancestors - Blog comment by lkessler - 3 Oct 2017
Joe: I'm hoping to come up with a method of chromosome mapping using the match information and then display the map in the DMT output. If that is successful, then it will be an automated system that does what visual phasing does plus more (sometimes going back to generations further than grandparents). I think ...
198.
Deep Ancestors - Blog comment by jbissett - 2 Oct 2017
Determining crossover points is a key factor when developing a Visual Phasing chromosome map of each chromosome for a given group of ancestors. Determining earlier sub-groups is certainly an important additional capability. Now that DMT can be used for GedMatch results as well as FTDNA, DMT can provide the ...
199.
Triangulation does NOT mean IBD - Blog comment by lkessler - 27 Sep 2017
Debbie: I agree with everything you say (except maybe one thing, which I'll likely write about in a future blog post).
I was specifically talking about triangulation. Yes of course, a match between two people can be IBD. But the point of the article was to dispense with the notion that triangulation means ...
200.
Triangulation does NOT mean IBD - Blog comment by debbiek - 27 Sep 2017
I presume you are using triangulation here to mean that three people match on the same segment and that close relatives (eg, parents) cannot be included in the triangulation as they are on the same leg of the triangle as you. If so, it is not true to say that three people have to match on a segment for it to be ...
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Deep Ancestors - Blog comment by lkessler - 4 Oct 2017