Wei Dai comments on Experiment: Knox case debate with Rolf Nelson

Wei Dai 11 Jul 2011 3:17 UTC
0 points

If there’s a single lab contamination, the odds that it contaminates a likely murder weapon at the cottage is about .002.

I’m having trouble understanding this. Can you explain a bit more? How did you get .002?
- komponisto 11 Jul 2011 19:18 UTC
  1 point
  Parent
  My guess is it’s probably figured by assuming there are ~500 objects being examined by the lab. However, I would point out that contaminations are unlikely to be independent of each other, and are instead probably correlated via the general level of standards in the laboratory. In other words, if there is a single contamination, there are likely to be others as well (reported or not).
  - rolf_nelson 12 Jul 2011 4:03 UTC
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    My guess is it’s probably figured by assuming there are ~500 objects being examined by the lab.
    
    Correct, I’m guessing a mean of roughly 500 examinations per homicide investigation.
    
    ...if there is a single contamination, there are likely to be others as well (reported or not).
    
    Agree.