Data:Snoddy YDNA Summary Table

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Summary

The following table summarizes the results of the Snoddy YDNA project as of 27 May 2010. Results for 12 markers are publically available. It is not known if additional markers have also been tested.

Signature/
Test Subject		13231411 1115 12 12 11 14 13 30
A13231411 1115 12 12 11 15 13 31
B13231411 1115 12 12 11 14 13 30
C13231411 1115 12 12 11 14 13 30
D13231411 1115 12 12 11 14 13 30
E13231411 1115 12 12 12 14 13 30
F13231411 1115 12 12 11 14 13 30
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Analysis

Given the fact that only 12 markers are publicly available as results for the six test subjects, only a limited analysis is possible. One test subject (E) differs from the Modal Signature by one point mutations, and another (A) by two point mutations. Tests subjects A and E differ from each other by three point mutations.

The following provides interpretative data for 0-, 1- and 2- off test results when 12 markers are tested:

For a 12 marker test:

Markers
tested		Probability *Gnerations to MRCA
At 0, 1, and 2
Mismatches		This table shows the relationship between the number of markers tested, the number of mismatches observed, and the probability that the MRCA lies a certain number of generations back. For example, if persons A and B take the YDNA test for 12 markers, and show an exact match on all 12 markers, there would be a 50% chance that their common ancestor lay within the last seven generations back, and a 90% chance that he lay within the lasts 17 generations.
012
12 50% 7 17 - Even an exact match shows that the MRCA would lie within the last seven generations with a 50% probability. That should be interpreted to mean that about half the time the MRCA will lie earlier or later than 7 generations. This is almost meaningless in genealogical terms. However, a mismatch of more than 1 marker in a 12 marker test may suggest that there is no common ancestor in a genealogical meaningful timeframe. Thus, 12 marker tests can be used to "rule someone out", but can not be used to rule them in.
90%23 39 -
95% 29 47 -
25 50% P3 7 11A 25 marker test significantly improves the usefulness of YDNA test results. About half the time an exact match indicates that the common ancestor lay within the last three generations. To improve the probability to 95% level (near certainty), the number of generations to the MRCA is still sometime within the last 13 generations back.
90% 10 16 23
95% 1320 27
37 50% 2-34 6An exact match in a 37 marker test indicates that the MRCA lies within the last 2 to 3 generattions about 50% of the time, and within the last 7 generations 95% of the time. It is for this reason that a 37 marker test is sometimes recommended as the most cost effective test path.
90% 5 8 12
95% 7 10 14
67 50% 2 4 6Increaseing the number of markers to 67 only marginally improves the the information returned from a YDNA test.
90% 4 812
95% 6 9 14

* X% probability that the MRCA was no further back than this number of generations, given the number of mismatches shown
Data from FTDNA 27 May 2010

Most of the test results in the Snoddy yDNA tests show an exact match on a 12 marker test. this suggests that 50% of the time the common ancestor of the test subjects would lie within the last 7 generations. If one chose, one could approximately convert the above data concerning "generation to MRCA" to "years to MRCA" by multiplying by an estimate of the time between generations. A value of between 20 and 25 years is often used for this purpose. If you assume a 22 year generation time, than at 50% probablity the Common ancestor would lie about 150 years prior to the birth of the test subjects. Assuming the test subjects were all about 50 years of age, then we get a MRCA sometime within the last 200 years (e.g., born around 1760). On the other hand, the MCRA would have occurred earlier than 1760 about half the time as well. As a result, its difficult to evaluate the meaning of a perfect 12/12 test result.

ON the otherhand, test subject A mismatched with most of the other test subjects by 1 marker (an 11/12 match). This tells us that the MRCA for test subject A, and most of the rest of the test subjects lay within the last 17 generations at a 50% probability, and at 47 generations at a 95% probability. Converting this into time to the MRCA, we get an estimate that at 50% probability the MRCA lay within roughly the last 400 years, and at 95% probability within the last 1100 years or so. the significance of this is that it is very unlikely that test subject A is closely related to any of the other test subjects, at least in a genealogically meaningful timeframe.

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