« Reply #3 on: Friday 20 October 17 18:03 BST (UK) »
I really believe that 12 markers (80 to 90 % error rates) and 25 markers (40 to 60 % error rates) tests should really be avoided as the false positive rates are just to high. They are useful if you have researched a line that you believe could be related and just want to see if there is a chance of being related. 37 markers (20 to 30 % error rates) is the first resolution to have reasonable false positive rates. But 67 markers is definitely the sweet spot: 1) it reduces the false positives by another 10 % or so (improvement but not radical); 2) It allows for YSNP prediction of branches in the 1,500 to 2,500 year range with over 95 % accuracy which is really great for haplogroup research (you may be able to eliminate a tier of SNP pack testing as well); 3) the least know advantage for many haplogroups, 67 markers and extensive YSNP testing allows charting of connections which really helps with advice for next steps for YSNP testing. You really have to belong to haplogroup that is very prolific (or very well YSTR tested as well) AND have a ton of Big Y tests yielding dozens of branches under a predictable YSNP in the 1,500 to 2,500 year range.
http://www.rcasey.net/DNA/R_L226/Haplotrees/L226_Home.pdfI am not a big believer these days for 111 marker upgrades - unless you find out very soon that you have many closer matches - then it helps. In the next year or two when the read lengths of NGS testing reaches 500 to 1,000 base pairs, 111 marker tests will no longer be required as you will be able to reliably extract out all of the FTDNA 111 markers in the new future from NGS tests. Once that happens, 500 YSTRs will be used vs. 111 markers (but this resolution will require some very costly software to properly analyze with so many markers involved).
Casey - Tipperary or Clare, Ireland
Kelly - Ireland
Brooks, Bryan, Shelton (2), Harper, Williamson - England
Tucker, Arrington, Stevenson, Shears, Jarvis - England
Hill (2), Reed, Olliff, Jackson, Potter, Cruse, Charlton - England
Davis. Martin, Ellison, Woodward, Alderson - England
Pace - Shropshire, England
Revier - Netherlands
Messer - Germany
Wininger - Switzerland