In fact I believe the fallacy you are referring to is known as the
Sir Roy Meadow calculated the odds of 2 SIDS in the same family to be
73 million to 1. Sally Clark (the accused) was later released from
prison when a mathematician estimated the relative likelihood of
murder VS SIDS in the same family to be quite different. He concluded
that 2 infants sre 9 times more likely to be SIDS victims than murder
I also think that the Prosecutor's Fallacy was also used by O.J.
Simpson's attorney. What a mess...
Jean Levasseur MD, MSc
Joliette, QC, Canada
Le 09-10-09 à 06:42, Ronan Conroy a écrit :
> On 8 DFómh 2009, at 17:14, Maconochie, Ian K wrote:
> This is not necessarily true - see Prof Meadows, paediatrician in Uk
> on the probablity of serial cot deaths! There may be predilections
> to their occurence which negate the routine estimation of risk.
> This is exactly the fallacy of Prof Meadows - he argued that cot
> deaths were so rare that the chances of a second one happening to
> the same family were utterly remote, so some factor other than
> chance had to be at work. His argument is flawed for three reasons:
> 1. The fact that you have had a cot death in the house does not
> alter your chances of having another one. If you have a son, your
> chances of your second child being a son are 50%, the same as they
> were when you had no children. More formally, the events are
> independent, so the probability of one event is uninfluenced by the
> occurrence of the other (but see 3 below)
> 2. Prof meadows argued that two cot deaths are so unlikely that they
> cannot simply be a coincidence, but actually one cot death is so
> unlikely that, were we to follow his argument, we would declare foul
> play each time a cot death happened. The fact that something is
> unlikely does not prevent it from happening.
> 3. He ignored the possibility of a common underlying mechanism. Many
> conditions cluster in families due to shared genes and environment.
> For this reason, the argument that the events are independent is
> hard to sustain. And the effect of shared mechanism is to make
> multiple events more likely, not less.
> The whole case was a dreadful example of the utter failure of the
> legal system to understand probabilistic reasoning.
> Ronan Conroy
> [log in to unmask]<mailto:[log in to unmask]>
> Royal College of Surgeons in Ireland
> Epidemiology Department,
> Beaux Lane House, Dublin 2, Ireland
> +353 (0)1 402 2431
> +353 (0)87 799 97 95
> +353 (0)1 402 2764 (Fax - remember them?)
> P Before printing, think about the environment