6 ms·

Speaking as a non-expert, it sounds too good to be true with the regular reports of false-positives and false-negatives from DNA testing. I'm with this person:

Speaking as a non-expert, it sounds too good to be true with the regular reports of false-positives and false-negatives from DNA testing. I'm with this person: They did something illegal to save lives.

vba616 4y ago
It seems reasonable that DNA evidence should not be used to convict someone alone, but if it's used as a starting point to find other evidence, well and good. Couldn't that other evidence be perfectly legal but not publicized yet?
asdff 4y ago
These reports are not regular to be honest... "Think of it this way: There are many thousands of paintings with blue backgrounds, but fewer with blue backgrounds and yellow flowers, and fewer still with blue backgrounds, yellow flowers, and a mounted knight in the foreground. When a forensic analyst compares alleles at 13 locations—the standard for most labs—the odds of two unrelated people matching at all of them are less than one in 1 billion." 1 In the past, there were issues with not getting these 13 sites sufficiently covered and losing statistical power. Today, to get around issues of certain markers dropping out for different reasons and to continue to ensure high statistical power, the FBI uses 20 markers now and samples must have a sufficient number of markers covered to be considered. 2 1. https://www.theatlantic.com/magazine/archive/2016/06/a-reasonable-doubt/480747/ https://www.theatlantic.com/magazine/archive/2016/06/a-reaso... 2. https://www.nist.gov/news-events/news/2016/12/nist-research-enables-enhanced-dna-fingerprints https://www.nist.gov/news-events/news/2016/12/nist-research-...
- tinus_hn 4y ago
  > the odds of two unrelated people matching at all of them are less than one in 1 billion. Sounds like on a world with 7 billion people for each crime there are on average 7 people that can be convicted using the incontrovertible evidence delivered by the DNA lab.
  - asdff 4y ago
    Do all 7 people have a motive and no alibi? Probably not.
    - tinus_hn 4y ago
      Who knows, chances are most of them are related.
      - asdff 4y ago
        I think you know what a rare lightning strike of an even this would be and how without DNA evidence, conclusions would be even more dubious.
        tinus_hn 4y ago
        Sorry, if the chances are one in a billion, and there’s 7 billion to choose from it’s actually not rare at all. That’s why you should be very careful to either use this kind of evidence either to find a suspect or as proof, and not both. But I’m sure we all know there’s plenty of ‘tough on crime’ judges that wouldn’t care about convicting someone based on this kind of seemingly rare occurrence.
        asdff 4y ago
        Every piece of evidence presented in the court room has some probability of implicating someone else. That's why multiple pieces are generally presented.

vba616 4y ago

It seems reasonable that DNA evidence should not be used to convict someone alone, but if it's used as a starting point to find other evidence, well and good. Couldn't that other evidence be perfectly legal but not publicized yet?

asdff 4y ago

These reports are not regular to be honest... "Think of it this way: There are many thousands of paintings with blue backgrounds, but fewer with blue backgrounds and yellow flowers, and fewer still with blue backgrounds, yellow flowers, and a mounted knight in the foreground. When a forensic analyst compares alleles at 13 locations—the standard for most labs—the odds of two unrelated people matching at all of them are less than one in 1 billion." 1 In the past, there were issues with not getting these 13 sites sufficiently covered and losing statistical power. Today, to get around issues of certain markers dropping out for different reasons and to continue to ensure high statistical power, the FBI uses 20 markers now and samples must have a sufficient number of markers covered to be considered. 2 1. https://www.theatlantic.com/magazine/archive/2016/06/a-reasonable-doubt/480747/ https://www.theatlantic.com/magazine/archive/2016/06/a-reaso... 2. https://www.nist.gov/news-events/news/2016/12/nist-research-enables-enhanced-dna-fingerprints https://www.nist.gov/news-events/news/2016/12/nist-research-...

tinus_hn 4y ago
> the odds of two unrelated people matching at all of them are less than one in 1 billion. Sounds like on a world with 7 billion people for each crime there are on average 7 people that can be convicted using the incontrovertible evidence delivered by the DNA lab.
- asdff 4y ago
  Do all 7 people have a motive and no alibi? Probably not.
  - tinus_hn 4y ago
    Who knows, chances are most of them are related.
    - asdff 4y ago
      I think you know what a rare lightning strike of an even this would be and how without DNA evidence, conclusions would be even more dubious.
      - tinus_hn 4y ago
        Sorry, if the chances are one in a billion, and there’s 7 billion to choose from it’s actually not rare at all. That’s why you should be very careful to either use this kind of evidence either to find a suspect or as proof, and not both. But I’m sure we all know there’s plenty of ‘tough on crime’ judges that wouldn’t care about convicting someone based on this kind of seemingly rare occurrence.
        asdff 4y ago
        Every piece of evidence presented in the court room has some probability of implicating someone else. That's why multiple pieces are generally presented.