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Old 08-29-2017, 04:10 AM
 
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The New York Times ran a front page article today about limitations of DNA testing for genealogy.


See https://www.nytimes.com/2017/08/28/s...-ancestry.html
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Old 08-29-2017, 07:46 AM
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Quote:
Originally Posted by RDM66 View Post
The New York Times ran a front page article today about limitations of DNA testing for genealogy.


See https://www.nytimes.com/2017/08/28/s...-ancestry.html


That's not exactly what they are referring to, the article is talking about ethnicity estimates. These tests are really good at estimating which continent the SNP's arose in but not so good at spitting it by national boundaries. For example they are really consistent at estimating what percentage arose in sub-Saharan Africa vs Europe but it becomes much more fuzzy when separating German from French as an example.
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Old 08-31-2017, 12:08 PM
 
Location: Colorado (PA at heart)
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Yes, the fact that ethnicity reports are only really accurate on a continental level but on a sub-continental level are only an estimate and should not be taken literally is something I've been harping on about for years now. They are interesting but should be taken with a grain of salt.
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Old 09-01-2017, 05:05 AM
 
Location: The Triad (NC)
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Quote:
Originally Posted by PA2UK View Post
Yes, the fact that ethnicity reports are only (currently) accurate on a continental level but ...
They are interesting but...
As millions more participate the data required for greater accuracy accumulates.

The next level of complication is the relative mobility available in the last 300 years
and how that opened up greater opportunity for a greater level of mixing at ever greater distances.

Last edited by MrRational; 09-01-2017 at 05:17 AM..
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Old 09-01-2017, 01:35 PM
 
Location: Colorado (PA at heart)
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Quote:
Originally Posted by MrRational View Post
As millions more participate the data required for greater accuracy accumulates.

The next level of complication is the relative mobility available in the last 300 years
and how that opened up greater opportunity for a greater level of mixing at ever greater distances.
Please don't misquote me by editing my comments - I said what I said, not what you wanted me to say.

The ethnicity reports don't change based on testers - only increases to the sample groups they use for comparison will change the ethnicity report. That does happen occasionally, but not regularly and arguably although it may change the results, it will not necessarily make them more accurate. The crux of the matter is that sub-continental regions have been intermixing for too long and therefore share too much DNA to ever be able to always tell them apart with any accuracy. No matter how big the sample groups - even if you used everyone in a nation as a sample group, they will still share too much DNA with neighboring regions to always be able to tell them apart.
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Old 09-03-2017, 02:16 PM
 
Location: The Triad (NC)
29,877 posts, read 65,685,621 times
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Quote:
Originally Posted by PA2UK View Post
The crux of the matter is that sub-continental regions have been intermixing for too long
and therefore share too much DNA to ever be able to always tell them apart with any accuracy.

No matter how big the sample groups - even if you used everyone in a nation as a sample group,
they will still share too much DNA with neighboring regions to always be able to tell them apart.
It's this sort of unqualified absolute statement that cries out for editing.
Let alone the absurdum expectation of 100% accuracy you seem to believe is needed or even being discussed.
Don't make that sort of statement and you won't have the shortcoming pointed out.

As millions more participate the data required for greater accuracy accumulates.
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Old 09-03-2017, 08:58 PM
 
Location: Georgia, USA
25,383 posts, read 30,166,867 times
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Quote:
Originally Posted by MrRational View Post
It's this sort of unqualified absolute statement that cries out for editing.
Let alone the absurdum expectation of 100% accuracy you seem to believe is needed or even being discussed.
Don't make that sort of statement and you won't have the shortcoming pointed out.

As millions more participate the data required for greater accuracy accumulates.
Millions more participating does not get around the fact that there is no DNA that is so unique it will be able to pinpoint someone's ancestry to a particular town in a particular country.
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Old 09-03-2017, 09:01 PM
 
Location: Raleigh
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Sort of like a horoscope predicts character or your future?
"only more vague"
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Old 09-04-2017, 09:05 AM
 
Location: Colorado (PA at heart)
9,259 posts, read 14,323,197 times
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Quote:
Originally Posted by MrRational View Post
It's this sort of unqualified absolute statement that cries out for editing.
Let alone the absurdum expectation of 100% accuracy you seem to believe is needed or even being discussed.
Don't make that sort of statement and you won't have the shortcoming pointed out.
I never said anything about 100% accuracy - you seem to read what you want to read in my comments, not what I've actually said.

Do you have evidence that says people within different sub-continental regions don't share a lot of DNA? Because all evidence I've seen says that they do.

Quote:
As millions more participate the data required for greater accuracy accumulates.
Repeating yourself doesn't make it true. As I said, the ethnicity reports are based on sample groups, those are separate from the millions buying and taking the test. Testers aren't used for samples.

For example, here is AncestryDNA's reference panel - these are the sample groups used for the ethnicity report:

https://www.ancestry.com/cs/dna-help...ity/whitepaper

V2 Reference Panel

The updated AncestryDNA ethnicity estimation V2 reference panel contains 3,000 samples carefully selected as described to represent 26 distinct global regions (Table 3.1), each with a somewhat distinct genetic profile. As a comparison, our Beta panel represented only 22 distinct global regions.

Region # Samples
Great Britain 111
Ireland 138
Europe East 432
Iberian Peninsula 81
European Jewish 189
Scandinavia 232
Italy/Greece 171
Europe West 166
Finland/Northwest Russia 59
Africa Southeastern Bantu 18
Africa North 26
Africa South-Central Hunter-Gatherers 35
Benin/Togo 60
Cameroon/Congo 115
Ivory Coast/Ghana 99
Mali 16
Nigeria 67
Senegal 28
Native American 131
Asia Central 26
Asia East 394
Asia South 161
Melanesia 28
Polynesia 18
Caucasus 58
Near East 141
Total 3000
Table 3.1: The Final AncestryDNA V2 Ethnicity Reference Panel

There are currently 3000 samples - not millions.
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Old 09-04-2017, 09:09 AM
 
Location: Colorado (PA at heart)
9,259 posts, read 14,323,197 times
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Quote:
Originally Posted by Crashj007 View Post
Sort of like a horoscope predicts character or your future?
"only more vague"
They are not like a horoscope at all. Although the ethnicity reports are an estimate should not be taken too literally, there is a scientific basis to them, and at a continental level, they are fairly accurate.
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