TiP: a poor tool

I regularly see folks with a yDNA test who are completely misusing and misunderstanding the FTDNA TiP tool.  If I had my choice, only Project Administrators could access TiP info.  That may surprise you - so here's why I say that:

There is NO BASIS for talking about needing a certain % or number of generations when using the TiP comparison tool. 

This Tool is a statistical analysis for assessing the probabilities on large numbers of events.  When applied to a single situation, it is still accurate - but really VERY disappointing and not very useful or satisfying once you understand what it is saying.  It is ONLY valid if you appropriately interpret the information. 

The appropriate interpretation is that you use the entire range of possibilities.  In the example below, any separation from 1 generation to more than 16 generations can be the number of generations that separate me from Dale with our 65/67 match and still be consistent with the TiP report.  (Dale and I guess that our paper trails will connect in 7-9 generations if we ever find the paper trail connection)

When you are told that at 2 generations the percentage is 16.74% (my comparison with Dale at 67 markers - a GD=2), this means that 674 of 10,000 men will share a most recent common ancestor with their match at 2 generations or less.  (For 10,000 random men who have a known connecting paper trail with their match and are GD=2 at 67 markers)

When you are told that at 4 generations the percentage is 46.67%, this means that 4667 of 10,000 men will share a most recent common ancestor with their match at 4 generations or less.  (For 10,000 random men who have a known connecting paper trail with their match and are GD=2 at 67 markers)

You ARE NOT looking for the level above 50% or above 90%.  You are also not correct in simply stating that the number of generations correlating to 50% or 90% is the specific separation you have with your match.  (it might be true - but so are all of the other possibilities

 

Bottom Line: accept that the matches listed by FTDNA are your genetic kin.  Assume that PROBABLY but not CERTAINLY, the matches with the fewest mutations are your closest kin.  When in doubt, ask your administrator or read our interpretation guide in "DNA the Smart Way":  www.worldfamilies.net/smart

Terry