Interesting comparison between FtDNA and Ancestry over on Gedmatch.

[ltd-jean-pull]

One of our FamilyFinder matches has recently tested at Ancestry. She had already uploaded the FtDNA to Gedmatch and has just uploaded her Ancestry one as well.

Quite a few little pink segments (under 5cM....which generally don't matter, but sometimes they do) aren't showing as matching. Whether this is due to the new Ancestry chip or not I'm not sure.

[ltd-jean-pull]

On Gedmatch I've just compared the kit of a random matching stranger (we'll call him Bill) who has an Ancestry kit which matches both of Mary's kits.

There is a 6.7cM segment on one chromosome that is showing as matching between Bill's Ancestry kit and Mary's FF kit. This segment is not as matching between Bill's Ancestry kit and Mary's Ancestry kit.

There are other shorter segments not showing as well.

[mabrams]

AncestryDNA has an algorithm called Timber where they remove segments or parts of segments that are IBS. They call them pile-ups because the number of matches at that segment seems unrealistically high.

GedMatch shows the entire segment(s). So the amount on GedMatch is (very)roughly 25% or so higher.

To be honest when I have looked at my AncestryDNA segments, vs the full segment at GedMatch, I rarely see these pile-ups. This would be via the Matching Segment tool from Tier One.

[prairielad]

...

There is a 6.7cM segment on one chromosome that is showing as matching between Bill's Ancestry kit and Mary's FF kit. This segment is not as matching between Bill's Ancestry kit and Mary's Ancestry kit.
....

Out of curiosity, what chromosome and what are the start/stop positions...

[ltd-jean-pull]

Out of curiosity, what chromosome and what are the start/stop positions...

Chr9 136862132 to 138563810