yDNA match percentages so you can determine which test to do

Lets consider for example a 100% match on a 12 marker test tells you that there is a 90 percent probability that your common ancestor lived within the last 48 generations and a 50 percent probability that he lived within the last 15 generations.

A 100% match on the 37 market test narrows the time frame further showing a 90 percent probability that your common ancestor lived within the last 16 generations and a 50 percent probability that he lived within the last five generations

37 of 37 50% was no longer than 2 generations, 90% that no longer than 5 generations, 95% no longer than 7 generations
36 of 37 50% was no longer than 4 generations, 90% that no longer than 8 generations, 95% no longer than 10 generations
35 of 37 50% was no longer than 6 generations, 90% that no longer than 12 generations, 95% no longer than 14 generations

A 100% match on the 67 market test narrows the time frame further showing a 90 percent probability that your common ancestor lived within the last 4 generations and a 50 percent probability that he lived within the last 2 generations

67 of 67 50% was no longer than 2 generations, 90% that no longer than 4 generations, 95% no longer than 6 generations
66 of 67 50% was no longer than 4 generations, 90% that no longer than 8 generations, 95% no longer than 9 generations
65 of 67 50% was no longer than 6 generations, 90% that no longer than 12 generations, 95% no longer than 14 generations

Put together by Jill 2011