How accurate is GEDmatch's admixture utility for recent ancestry?

Question

It is more accurate than I realized.

I've found ten people in WikiTree who can trace all their ancestors back at least four generations to the same country and have a GEDmatch ID:

http://www.wikitree.com/index.php?title=Space:Autosomal_DNA_Ethnic_Admixture_and_Ancestry&public=1

Today I discovered that GEDmatch's Oracle-4 attempts to pinpoint your [modern] ethnic group of origin.  https://www.gedmatch.com/gedwiki/index.php?title=Admixture

Oracle-4 shows the three persons in WikiTree with all English ancestry as

1 Southwest_English @ 3.794286, 2 Southeast_English @ 3.947610

1 Southeast_English @ 2.674424, 2 Southwest_English @ 2.747479

1 Southeast_English @ 2.653272, 2 Southwest_English @ 3.738122

The one person with all Italian ancestry:

1 North_Italian @ 5.280625, 2 Tuscan @ 9.284982

The odd ones are the person with all Danish ancestry:

1 North_German @ 6.236578, 2 Swedish @ 6.555415, 3 Danish @ 6.688893

and the person with all German ancestry:

1 South_Dutch @ 2.905174, 2 West_German @ 3.139654, 3 French @ 7.970687

The others have old Family Finder GEDmatch IDs.

Comments

My most accurate of all the companies and those within Gedmatch is K-15

Answer 1

I just ran the Eurogenes one as according to FTDNA's newest version of Origins I am  European99%

 British Isles57% , West and Central Europe36%,  Iberia6%,   and trace at <2% Finland

It seemed to fit pretty well what I know of my paper genealogy