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    Facthunts

    What the O.J. Simpson jury didn’t know (and schools should teach)
    We’re just not good with probabilities. But perhaps we can learn to be
    4 Comments 1 March 2014 Rory Sutherland

    During the O.J. Simpson trial, the prosecution made much of the fact that Simpson had a record of violence towards his wife. In response, Simpson’s legal team argued that, of all women subjected to spousal abuse, only one in 2,500 was subsequently killed by the abusive husband. It was hence implied that, since the ratio of abusers to killers was so high, any evidence about the accused’s prior violent behaviour was insignificant.
    This sounds plausible. However, there is another way to consider the statistics. According to the German academic Gerd Gigerenzer, we are not trying to predict whether a husband will murder his wife: Simpson’s wife inarguably had been murdered, so instead, we should ask the question backwards: given that a battered wife has been murdered, what are the odds that the husband did it? Gigerenzer calculates that ‘the chances that a batterer actually murdered his partner, given that she has been first abused and then killed, is about eight in nine’.
    This is a case where a statistical sleight of hand normally called ‘the prosecutor’s fallacy’ worked for the defence. What is interesting is not merely that we are confused but the degree of our confusion: the presentation of the data affects our judgment by factor of thousands: from 0.04 per cent to 90 per cent. We need to be alert to this kind of error, particularly since computers and ‘big data’ make it easy to generate spurious but plausible statistics on almost any subject.

    High-profile criminal cases seem plagued by peculiar mental biases. In particular, they seem to cause people to polarise around only two opposing theories of ‘what happened’.
    I felt slightly vindicated when I finally heard that the British police were investigating the possibility that the disappearance of Madeleine McCann was the result of a burglary attempt gone wrong. Since planned abduction by a paedophile is so rare, it struck me as odd that no one much considered this more probable option.

    Press and internet commentary seems to amplify the either/or effect. If you want to see this tendency at its most extreme, the online reaction to the trials of Amanda Knox and Raffaele Sollecito is a textbook case. The two camps, the Colpevolisti and Innocentisti, operate entirely separate, partisan websites: which site you see first will affect your assessment of Knox and Sollecito’s guilt enormously. I have to say here that using Occam’s razor — or even Occam’s nasal hair-trimmer — should incline you towards believing the pair are more likely to be innocent than guilty. Burglaries gone wrong seem more common than sex games turned murderous. The investigating authorities formulated theories before evidence was available, and were reluctant to modify them, instead creating further bizarre theories to support their initial assumptions — a tendency known as ‘privileging the hypothesis’. Had the DNA and fingerprint evidence implicating Guede been available at once, would the investigation have proceeded as it did? Almost certainly not.

    But few commentators discuss the case in terms of probabilities — it is all about certainty first, evidence later. This tendency is probably innate. But Gigerenzer believes it can be corrected: ‘Schools spend most of their time teaching children the mathematics of certainty — geometry, trigonometry — and spend little if any time on the mathematics of uncertainty. Statistical thinking could be taught as the art of real-world problem solving.’
    German schools are beginning to adopt his approach. Britain (and Italy) should follow.
    Rory Sutherland is vice-chairman of Ogilvy Group UK.
    My computer thinks I'm gay
    What's the difference anyway
    When all the people do all day
    Is stare into a phone

    #2
    I really though the thread title was play on words!

    Interesting reading though. The maths of uncertainty. Lots to think about really.
    Tic-Toc. POC and DOC. Stop the clock.

    Comment


      #3
      It was. Certain folk - including but not limited to some, many or fewer who may currently be on a long holiday - are prone to making selective use of stats to present "data" of dubious integrity.
      Tis but a scratch.

      Comment


        #4
        Ah. I thought it was a reference to Oscar Pistorius!
        Please support Milford Hospice. Click here to donate.

        Comment


          #5
          Just thought it was an interesting article on the way stats can be deliberately misused, often by people with an agenda. Its a pity ADHD isnt around to offer his opinions
          My computer thinks I'm gay
          What's the difference anyway
          When all the people do all day
          Is stare into a phone

          Comment


            #6
            It's like the "gateway drug" argument against legallising Dope.

            "practically everyone who takes heroin started out on Dope"

            Rather than "how many of those who have ever taken dope have taken heroin."

            Comment


              #7
              Originally posted by Piquet View Post
              It's like the "gateway drug" argument against legalising Dope.
              As always, It all depends on your outlook in how you see these things.

              All I'll say is. What is researched, and what isn't, and by what method, and for what purpose, is decided by commercial interest, by fashion and by personal preference, usually not some idealistic search for the truth.
              The axe that cuts the tree can easily forget, but the tree thats been cut will not forget.

              Originally posted by the plastic paddy
              Gwan the Welsh

              Comment

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