Small Segment Stats
Ancestry DNA Matches who share 6-7cM and have a known MRCA with me: 1,160.
Total Ancestry DNA Matches at any cM level: 7450.
About 15% of my DNA Matches with a known MRCA share only 6-7cM.
This is NOT a statement linking DNA and Ancestors.
This IS a statement about the many true cousins we will not see in our Match lists because the current threshold at AncestryDNA is 8cM.
I’m glad I Dotted and saved some of my 6-7cM Matches when Ancestry made the threshold change – it was a fraction of the total. I wish I’d have saved them all…
To end on a higher note – I still have 2,600 other 6-7cM Matches to work with – many of them are being determined as close cousins to known MRCA Matches by using ProTools.
[22DF] Segment-ology: ProTools Part 24 – Small Segment Stats by Jim Bartlett 20250221
segment-ology 
It’s unfortunate that some folk get combatitive about the whole “small segments are harmful” thing. Ancestry do so much good and inadvertently/unintentionally create great swathes of damage like an elephant dancing in a tomato patch. People get attached to their preferred toolsets and it’s as if a Stockholm Syndrome sets in.
LikeLiked by 1 person
Peter, As a life-long gardner, I love your analogy (although in my case it was deer, until I put up an 8″ high fense). I’m so glad that ProTools has been able demonstrate that many small-segment Matches are well within a genealogy time frame. I am *still* adding Matches to my Common Ancestor Spreadsheet – every day – using ProTools. Jim
LikeLike
That’s helpful Jim … thank you. Keep it up.
LikeLike
Jim … these observations and suggestions have been great. I did save virtually all of the 6 cM / 7 cM matching to both my father’s kit and his full brothers kit … AND … at least one cousin kit in the mixture. They have all proven to be useful as I plod my way through them using the Pro Tool(s) and taken notes.
LikeLike
John – Great! And thanks for the kind feedback. I’m still only about 1/3 through my spreadsheet – rechecking each MRCA line with ProTools and adding in various cousins. It’s a brutal slog – I often take an afternoon nap to rest my eyes. But the result will be a stong, vetted genealogy baseline. I can then go back to Clusters and Triangulated Segments to tie it all together… Jim
LikeLike
My brain is still trying to update me on the overall value of what I’m recording … I’m noting in the “NOTES” field all Shared Matching over a threshold … usually 75 cM or greater (and then I run out of character space). But that has confirmed and reconfirmed relationships in a real demonstrable way. I’ve been reading your blog on this since the inception … and I agree … Ancestry has a strong tool here .. I hope they continue to improve it rather than go the other direction.
LikeLike
John – Since the 1990s I have kept a Word doc for each of my Ancestors – in an outline format by generations with a time line of extracted records (often hyperlinked). Then I got busy with a Tree at Ancestry. And then I found the value of keeping tract in the Notes. I quickly found the top line in the Notes was very important as it showed in a Shared Match list. When I started my Common Ancestor spreadsheet, I found myself recording the same info in 3 places: Ancestry online Notes, my Word doc and the MRCA Spreadsheet – too much… So I’ve backed off of the Notes to only the MRCA info for Matches with that; and some other Note for others – including, like you, some of the top close Matches from ProTools. My thinking now is that the spreadsheet is handy and flexible and searchable. More of a firm “grid” of sorts. But the spreadsheet shortcoming is “no records”; so I’m using the Word docs for that [the free FamilySearch AI tool is great for that – easy search of many microfilms a lot easier than scrolling and/or the page turning I used to do in courthouses… Jim
LikeLike