Originally posted by fmoakes
Keep in mind the difference between haploTYPE and haploGROUP. Your haploTYPE is your series of STR results (ie, your markers). For every 12-marker Y-DNA test, FTDNA predicts your haploGROUP based on your 12-marker haploTYPE. How? In most cases, there are already people in the FTDNA database and in Dr. Hammer's database with the same 12-marker haploTYPE as you. One or more of those people had their haploGROUP confirmed by SNP test. So FTDNA can use this information to predict the haploGROUP for future testees who have the same haploTYPE. They don't do SNP tests for every person to determine their haploGROUP.
However, there may be times when someone comes along with a rare 12-marker haploTYPE that is not already in the FTDNA database. I recall reading on the boards that if FTDNA can't reasonably predict the haploGROUP for this person based on haploTYPEs already in the databases, they will do a free SNP test to determine the person's haploGROUP. Providing the haploGROUP is part of their service, so they won't just guess at it or leave it blank. Doing the SNP test in this case is a necessary part of providing the results back to the customer. And, it helps to contribute to FTDNA's database so that when someone else comes along with this rare haploTYPE, they'll now have the information to predict the second person's haploGROUP.
It's possible that I'm remembering this wrong -- I'll see if I can find the post(s) that mentioned this. In the meantime, here's a page on FTDNA's website that discusses some of this:
Elise
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