Accuracy of DYS figures

[john franks]

After reading a number of threads and seeing the importance attached to the DYS values I was lead to wonder if FTDNA, or anyone else, has quoted the accuracy that can be expected of these figures. For example if the number of alleles quoted for a given locus is, say, 25 then what is the chance that it might in fact be 24 or 26? Knowing this might not matter in the greater scheme of things but could enable us to make a better interpretation of our results when matches are getting close.

John

[rucksack]

I am assuming you didn't really mean "accuracy".

If you did, my apologies.

Check this link: http://www.smgf.org/ychromosome/marker_details.jspx

Just click on any allele number.

[T E Peterman]

My reading of the initial posting is that you don't mean frequency. You want to know what the odds are that the count is wrong. I can't say, but if you suspect that the count is wrong, you might have Family Tree DNA check it again; or have another lab count the markers at the locus.

Timothy Peterman

[Jim Barrett]

Very High For FTDNA

I don't know why anyone would test with any other company so I don't worry about the accuracy of other companies. FTDNA has told me that include samples with known results in every batch to have a way to verify the process.

If you question their result they'll will rerun the test for a fee and the last I knew that fee would be returned if they found that they had made an error.

[john franks]

Just to clarify one or two things: I did mean accuracy (though precision might be a better term), I am not questioning ftdna's results and I am not thinking of moving to another company.

I am simply aware that figures produced by laboratories in other spheres of activity have a degree of uncertainty attached to them. If ftdna's numbers are pretty well absolute then I am delighted!

Thanks for replies - and the smgf reference.

John

[wmccown]

Accuracy of DYS Figures

If subjective experience can ease your mind, a descendant of my great grandfather's younger brother matches me at 12, 25, 36/37 and 66/67. Even the one mutation is consistent with one of the Maguire families where my matches are concentrated.

All of my matches at 37 markers who were tested at 67 markers survived at 67 markers and there are 18 of those and include matches at 60, 61, 62 and 63/67 and I have hopes of another at 64/67. This degree of consistency satisfied me that my FTDNA test results are accurate.

And speaking of accuracy, in a casual review of LDS family trees, it is the accuracy and honesty of family trees that is of much greater concern to me.

The grandmother of a friend was a lifelong member of the LDS, baptized in the temple. Someone sent in a family tree that listed the friend's grandmother as a male. She definitely was not. When notified of the error, LDS refused to remove or correct the error.

[rucksack]

SMGF has made an error on my surname.

They have been notified countless times.

The error is still there.

Apparently, they believe that they can make no mistakes!

[PDHOTLEN]

SMGF has made an error on my surname.

They have been notified countless times.

The error is still there.

Apparently, they believe that they can make no mistakes!

SMGF also has not corrected my family tree information (via email communication). But I'll try sending them a written correction and see if that works. It still shows the old erroneous tree.

U5b2 & R1a1

[teyoung]

Knowing this might not matter in the greater scheme of things but could enable us to make a better interpretation of our results when matches are getting close.

I was tested by both SMGF and FTDNA. On the markers they have in common, both labs returned the same results. I wasn't really worried about accuarcy, am less worried now.

[john franks]

Very interesting that SMGF and FTDNA gave the same results.

I am sure that dna figures are more reliable than many of those obtained from the paper trail. I have come across errors in a marriage certificate, census returns, legal documents and the LDS.

[rucksack]

SMGF and FTDNA have been exact on results, though SMGF seems to have the silly habit of trickling in the results a few at a time over the course of a year or two.