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What's unsatisfactory is the way these companies present these results which implies a level of accuracy and precision which is unwarranted. "She also has Fren

What's unsatisfactory is the way these companies present these results which implies a level of accuracy and precision which is unwarranted. "She also has French and German ancestry (2.6 per cent) that her sister doesn't share." I assume from this that 23andMe is reporting the results to this level of accuracy (a tenth of a percent). For the sister who got 2.6% they are strongly implying a certainty that she has a small amount of French and German ancestry rather than what actually seems to be the case which is a small chance of some French and German ancestry. Since it seems their results are quite lacking in both precision and accuracy they should do a better job of reporting them and advertising them in a way that makes that clear.

truantbuick 8y ago
I can only speak for myself, but when I got one of these tests 6 years ago, I never got such an impression. They've updated my results several times since and I never feel hoodwinked as if I had been previously deceived; I'm always just curious to see what the latest estimates are. > I assume from this that 23andMe is reporting the results to this level of accuracy (a tenth of a percent). For the sister who got 2.6% they are strongly implying a certainty that she has a small amount of French and German ancestry rather than what actually seems to be the case which is a small chance of some French and German ancestry. You picked out the single biggest discrepancy they report in this article, and yet even that doesn't seem to indicate an actual inconsistency to me. I would tend to interpret those results to mean that for one twin, they felt sufficiently confident to call a portion of their DNA "French and German", while in the other it fell below that confidence threshold so it got thrown into the "Broadly European" share. This process already pretty much precludes objective perfection just based on what they're reporting. What does it mean for your ancestry to come 2.6% come from France? During what time period? What if it's on the border in one of those regions that switched hands several times? These are subjective decisions they have to make but it doesn't invalidate the whole test because occasionally you have enough evidence to call portion of your DNA "French and German" and sometimes you have to fallback to just calling it "Broadly European".
- ninth_ant 8y ago
  > This process already pretty much precludes objective perfection just based on what they're reporting. What does it mean for your ancestry to come 2.6% come from France? During what time period? What if it's on the border in one of those regions that switched hands several times? These are subjective decisions I think that’s the whole point of the complaint here. These companies pretend to have found overly precise results (which I’m sure are explained away to nothing in the fine print) and yet are subjective and lean heavily on guesswork.
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- Gimpei 8y ago
  23andMe told me that I was a quarter Italian. Seemed to have mixed that up with what I actually am: 50% middle eastern. For a while I wondered if there was some funny business in the family, but then my sister got the "right" percentages. This seems like a pretty huge error to me.
  - bitxbitxbitcoin 8y ago
    I know it might can be assumed from the context of the post and thread but are you talking about your twin sister or not? Just pointing out that the chance for funny business (in your family or at your birth or at these companies) is unknown but not necessarily zero.
  - toyg 8y ago
    Well, Italian and ME populations were basically the same thing for more than a thousand years (basically until the Islamic Conquest promoted piracy on the Mediterranean, making it fundamentally unsafe). So it might well be that you are carrying genes that most of the Italian population also carries, and viceversa.
  - hnnh44 8y ago
godelski 8y ago
I would argue that this is why significant digits count. You can't say something is 2.1374cm long when your error is +/-1cm. You can say it is 2cm long though.
- a11595 8y ago
  Significant digits is a calculation shortcut introduced to people freshman year in highschool. It's shorthand for error rate. 2.1374cm +-1cm is a completely different error range than "2." In fact, guess what - real equipment error rates are not integers like 1cm - it's something like "+-.96cm" . Your way literally takes results and makes them less accurate. Why in the world would they do that?
- jhall1468 8y ago
  I'm not sure why anyone thinks significant digits in any way informs error rate, and it's a little hyperbolic to suggest 4 significant digits with a whole number error rate, when they did 1 significant digit with a ~3% to ?% error rate.
  - aeternus 8y ago
    >I'm not sure why anyone thinks significant digits in any way informs error rate In the majority of technical fields the standard is to round the result so that the significant digits do correspond to error rate. https://www.ruf.rice.edu/~bioslabs/tools/data_analysis/errors_sigfigs.html https://www.ruf.rice.edu/~bioslabs/tools/data_analysis/error...
    - jhall1468 8y ago
      I'd expect that in academia for the most part. But this is a consumer product, so they aren't going to follow technical fields, and my hunch is that's for marketing reasons (it looks more authentic). But even then, rounding to the error rate is a standard practice, but it certainly does mean it's wrong or even unethical, it's just pointless not to. Unless of course your motivation is driven by marketing/sales.

truantbuick 8y ago

I can only speak for myself, but when I got one of these tests 6 years ago, I never got such an impression. They've updated my results several times since and I never feel hoodwinked as if I had been previously deceived; I'm always just curious to see what the latest estimates are. > I assume from this that 23andMe is reporting the results to this level of accuracy (a tenth of a percent). For the sister who got 2.6% they are strongly implying a certainty that she has a small amount of French and German ancestry rather than what actually seems to be the case which is a small chance of some French and German ancestry. You picked out the single biggest discrepancy they report in this article, and yet even that doesn't seem to indicate an actual inconsistency to me. I would tend to interpret those results to mean that for one twin, they felt sufficiently confident to call a portion of their DNA "French and German", while in the other it fell below that confidence threshold so it got thrown into the "Broadly European" share. This process already pretty much precludes objective perfection just based on what they're reporting. What does it mean for your ancestry to come 2.6% come from France? During what time period? What if it's on the border in one of those regions that switched hands several times? These are subjective decisions they have to make but it doesn't invalidate the whole test because occasionally you have enough evidence to call portion of your DNA "French and German" and sometimes you have to fallback to just calling it "Broadly European".

ninth_ant 8y ago
> This process already pretty much precludes objective perfection just based on what they're reporting. What does it mean for your ancestry to come 2.6% come from France? During what time period? What if it's on the border in one of those regions that switched hands several times? These are subjective decisions I think that’s the whole point of the complaint here. These companies pretend to have found overly precise results (which I’m sure are explained away to nothing in the fine print) and yet are subjective and lean heavily on guesswork.
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Gimpei 8y ago
23andMe told me that I was a quarter Italian. Seemed to have mixed that up with what I actually am: 50% middle eastern. For a while I wondered if there was some funny business in the family, but then my sister got the "right" percentages. This seems like a pretty huge error to me.
- bitxbitxbitcoin 8y ago
  I know it might can be assumed from the context of the post and thread but are you talking about your twin sister or not? Just pointing out that the chance for funny business (in your family or at your birth or at these companies) is unknown but not necessarily zero.
- toyg 8y ago
  Well, Italian and ME populations were basically the same thing for more than a thousand years (basically until the Islamic Conquest promoted piracy on the Mediterranean, making it fundamentally unsafe). So it might well be that you are carrying genes that most of the Italian population also carries, and viceversa.
- hnnh44 8y ago

godelski 8y ago

I would argue that this is why significant digits count. You can't say something is 2.1374cm long when your error is +/-1cm. You can say it is 2cm long though.

a11595 8y ago
Significant digits is a calculation shortcut introduced to people freshman year in highschool. It's shorthand for error rate. 2.1374cm +-1cm is a completely different error range than "2." In fact, guess what - real equipment error rates are not integers like 1cm - it's something like "+-.96cm" . Your way literally takes results and makes them less accurate. Why in the world would they do that?
jhall1468 8y ago
I'm not sure why anyone thinks significant digits in any way informs error rate, and it's a little hyperbolic to suggest 4 significant digits with a whole number error rate, when they did 1 significant digit with a ~3% to ?% error rate.
- aeternus 8y ago
  >I'm not sure why anyone thinks significant digits in any way informs error rate In the majority of technical fields the standard is to round the result so that the significant digits do correspond to error rate. https://www.ruf.rice.edu/~bioslabs/tools/data_analysis/errors_sigfigs.html https://www.ruf.rice.edu/~bioslabs/tools/data_analysis/error...
  - jhall1468 8y ago
    I'd expect that in academia for the most part. But this is a consumer product, so they aren't going to follow technical fields, and my hunch is that's for marketing reasons (it looks more authentic). But even then, rounding to the error rate is a standard practice, but it certainly does mean it's wrong or even unethical, it's just pointless not to. Unless of course your motivation is driven by marketing/sales.