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TMRCA Calculations
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This is difficult. As far as my calculator, just enter (for BigY) 1.e7 (or 10000000) for Number of Markers and 3.e-8
for mutation rate.
The hard part, very hard, is getting the number of nonmatching markers.
THIS CANNOT BE DONE USING JUST THE
FTDNA WEB PAGE RESULTS!!!
That's because in the "match" panels, if you try to
use the number of unique markers present in a person,
from their list, YOU CANNOT TELL IF THE OTHER PERSON
HAS AN ANCESTRAL RESULT FOR ALL THOSE MARKERS OR NOT!
This is because FTDNA is not taking into account nocalls.
To get a correct answer you MUST download the .bed
file and look up each and every marker in the match
lists to see if they are called in both files. The mutation
rates assume reliable markers only. So if one person
is a no-call you neglect that marker.
This process is merely painful. Its not hard. I have described how it do it several times.
On the other hand, if you just add up the number of
unshared unique variants for both people, a VERY
rough guess is to divide that number by two. I have not tried to measure it accurately.
I have tried several times to get FTDNA to mark which markers on the match list are no-calls in the "other person". And these attempts have all disappeared into a black hole. I tried to explain it and impress it on
FTDNA people at the I4GG conference and apparently it
did not register. Their inborn "simplicity is a commercial necessity even if its wrong" filter is too strong.
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Originally posted by lgmayka View PostSo for example, if YFull determines that you have 11 novel SNPs (best-quality + acceptable-quality only), then you and the nearest other YFull customer share a MRCA roughly 1540-1650 years ago.
Jim
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Originally posted by jbarry6899 View PostHow are people estimating TMRCA from BigY results?
One can then consider "best-quality" and "acceptable-quality" SNPs to be reliable. Each such SNP appears to correspond to 140-150 years of patrilineage.
So for example, if YFull determines that you have 11 novel SNPs (best-quality + acceptable-quality only), then you and the nearest other YFull customer share a MRCA roughly 1540-1650 years ago.
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Originally posted by 1798 View PostHave You asked any of the U152 project admins about the age of your group?
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Originally posted by jbarry6899 View PostThanks,
But I'm still confused about the process. The new McDonald TMRCA calculator appears to be able to use BigY data but I can't figure out how to enter the parameters. And Roberta Estes' blog makes a TMRCA estimate, but I can't determine how she did it. See: http://dna-explained.com/2014/06/24/big-y-matching/
Armando may know more about the process. Have You asked any of the U152 project admins about the age of your group?
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Thanks,
But I'm still confused about the process. The new McDonald TMRCA calculator appears to be able to use BigY data but I can't figure out how to enter the parameters. And Roberta Estes' blog makes a TMRCA estimate, but I can't determine how she did it. See: http://dna-explained.com/2014/06/24/big-y-matching/
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Originally posted by jbarry6899 View PostHow are people estimating TMRCA from BigY results? Yes, I know it's fraught with uncertainty and maybe useless, but I'm just curious.
So what is the process for looking at the total number of tested SNPs, novel SNPs and SNPs shared with matches to come up with an estimated GD and TMRCA?
Is anyone using Doug McDonald's updated TMRCA calculator for this purpose? If so, what are the input parameters you are using; I couldn't figure out what to enter. Calculator is here: http://dna-project.clan-donald-usa.org/tmrca.htm
Related question: When filtering BigY matches by terminal SNP, am I correct in assuming that those who have not tested to my terminal SNP on the FTDNA haplotree would appear in an upstream subclade? I ask because my FTDNA terminal SNP is not tested in BigY and I am trying to sort through my matches to determine which might be worth investigating.
Thanks,
Jim
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TMRCA Calculations
How are people estimating TMRCA from BigY results? Yes, I know it's fraught with uncertainty and maybe useless, but I'm just curious.
So what is the process for looking at the total number of tested SNPs, novel SNPs and SNPs shared with matches to come up with an estimated GD and TMRCA?
Is anyone using Doug McDonald's updated TMRCA calculator for this purpose? If so, what are the input parameters you are using; I couldn't figure out what to enter. Calculator is here: http://dna-project.clan-donald-usa.org/tmrca.htm
Related question: When filtering BigY matches by terminal SNP, am I correct in assuming that those who have not tested to my terminal SNP on the FTDNA haplotree would appear in an upstream subclade? I ask because my FTDNA terminal SNP is not tested in BigY and I am trying to sort through my matches to determine which might be worth investigating.
Thanks,
JimTags: None
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