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From: "Larry Dean" <>
Subject: [DNA] Time to Most Recent Common Ancestor
Date: Fri, 14 Nov 2003 14:37:23 -0800


I would appreciate some assistance understanding the probability of time to most recent common ancestor. The material FTDNA sent me with my 25-marker YDNA results includes some graphs of probability vs. Time to MRCA. If I eyeball those probability distributions I note that the mode of the 24/25 curve is about 7 generations and the median or 50% point is roughly 11 generations. Yet the table included with the FTDNA material says that the 50% probability point in that MRCA distribution is no longer than 18 generations.
Similarly, eyeballing the 23/25 graph indicates that the mode is about 14 generations and the median or 50% point is roughly 18 generations. But Ann Turner's MRCA calculator gives 28 generations for the median of this probability distribution.
Can someone help me understand this?
Larry Dean


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