What are the odds?

Discussion in 'Politics & Religion' started by Toonces, Apr 13, 2006.

  1. Toonces

    Toonces

    There was a show about a girl who claimed to have 'xray eyes' and diagnose a patient just by looking at them. Csicop did a test with 7 subjects, each with a particular ailment; she had to match each subject with a list of 7 ailments she was given.

    Csicop said that if she got 5 of 7 correct, they would admit that she had a definite abililty of some kind. They said that the odds of getting 5 right were 250:1. She ended up getting 4 correct. But they didn't mention the odds of getting 4. What are the odds?
     
  2. I remember that. It was a hot Russian chick, right?

    If she really has paranormal abilities, she can just take the James Randi challenge and claim her easy million bucks.

    $1,000,000 cash is offered to the first person capable of doing <b>anything</b> paranormal. Nobody has ever passed this challenge.
     
  3. Exactly.
     
  4. Toonces

    Toonces

    Yeah, it's the Russian chick.

    Of course, the counterargument that supporters of the paranormal use is that 'debunkers' like Randi set it up so that it's impossible to pass their tests.
     
  5. The odds of correctly matching 4 out of 7 by random guessing are about 1.2%, if my back of the envelope calculations are correct. It's actually not an easy problem to solve, as far as probability problems go.

    However, this was anything but random. In fact, the girl had major, incredible breaks gone her way, virtually by design, likely explaining each of her 4 so-called "matches." Here're the full accounts:

    http://www.csicop.org/specialarticles/natasha.html
    http://www.csicop.org/specialarticles/demkina.html

    If you don't have the time to read the whole thing, here's a brief, ROFLMAO excerpt from the first article, toward the end:


    Both inherent and unforeseen limitations of our test provided possible clues to the target conditions for some subjects. I already discussed the daunting task of finding seven appropriate subjects. We had to settle for a less than optimal set of subjects. These subjects differed sufficiently in outward appearance to provide possible clues about their conditions. Another problem occurred through two violations of the test protocol. Together these problems created the possibility for identifying the target conditions-by external, normal means-for the following four subjects:

    1. The "control" subject, the one who had no internal medical condition, was obviously the youngest of the group. He also looked in good physical condition and appeared much healthier. He was a good candidate for the person with no defects.
    2. The subject with the staples in his chest (because of major heart surgery) was male, the oldest of the group and looked the least healthy. He was an obvious choice for the person with the staples in his chest.
    3. A breach of protocol occurred on the first trial. Natasha posed a question and her interpreter translated it aloud in front of the subjects. The question, contrary to our protocol, allowed the subjects to know that Natasha was looking for the subject with part of her lung removed. Here it was possible that, knowing which condition Natasha was looking for, the subject with the missing lung might have given herself away through bodily reaction.
    4. After the test was over, I learned that Natasha and her companions, because of an apparent misunderstanding, had arrived at the test site before we had expected them. They waited outside the test building where they reportedly observed at least two of the test subjects climb the long flight of stairs and enter the test building. This breach of protocol may have provided them clues about which subjects did or did not have the artificial hip.

    We do not know if Natasha took advantage of the clues I've described in the previous four paragraphs. However, it is suggestive that these were just the four subjects for whom Natasha achieved her correct matches. The probability that she was relying upon nonparanomal clues increases when we consider her misses. She wrongly picked the subject who was wearing a baseball cap as the one who had the metal plate in his head. Conceivably, she picked this subject because one might assume (falsely in this case) that the subject was trying to cover a scar on his head. We should also emphasize that her failure to correctly match the subject with the metal plate in his head further argues against any fledgling paranormal powers. If she truly can see into bodies, she should have easily detected the large area of missing skull along with the metal plate covering the hole.

    Our test included five subjects for whom external clues were available concerning their internal condition. The clues correctly pointed to the true target condition for four subjects. The external clue for the fifth subject falsely pointed to the hole in the skull. In each of these five cases Natasha made her choice consistent with how the external clue was pointing.


    [underline mine]

    Yeah, very minor "outward appearance visual clues" and equally minor "violations of the test protocol." :D And she still couldn't match 5, after working on it for "more than 4 hours"? What a ridiculous, stupid, biased (in her favor) test that was. Get real.
     
  6. I think this is the matrix of odds:

    Correct Guesses %
    1 14.286%
    2 2.381%
    3 0.476%
    4 0.119%
    5 0.040%
    6 0.020%
    7 0.020%

    The odds for getting 6 out of 7 is the same for 7 out of 7, because once you have the first 6 correct, only one possibility remains for the last choice.