another Sally Clark?

“I don’t trust my own intuition when an apparent coincidence occurs; I have to sit down and do the calculations to check whether it’s the kind of thing I might expect to occur at some time and place.” D. Spiegelhalter

I just read in The Guardian an article on the case of the nurse Benjamin Geen, whose conviction to 30 years in jail in 2006 for the murder of two elderly patients rely on inappropriate statistical expertise. As for Sally Clark, the evidence was built around “unusual patterns” of deaths associated with a particular nurse, without taking into account the possible biases in building such patterns. The case against the 2006 expertise is based on reports by David Spiegelhalter, Norman Fenton, Stephen Senn and Sheila Bird, who constitute enough of a dream team towards reconsidering a revision of the conviction. As put forward by Prof Fenton, “at least one hospital in the country would be expected to see this many events over a four-year period, purely by chance.”

3 Responses to “another Sally Clark?”

  1. Michael Lew Says:

    This is a case where a little basic pharmacology might help as much as statistics. If Green injected patients with the curare-like paralysing agent that was found in the used syringe in his pocket then the patients who he revived would have had vivid memories of being paralysed while fully conscious. Presumably they didn’t report such memories.

  2. It’s funny that we never ever hear about such cases in France, is that because we are not even there yet, i.e. having statistical experts expert enough to question some of the court decisions based on statistical evidence?

    • Indeed, I think statistical arguments are poorly understood and accepted by judges and jurys alike. In the only case I was contacted by a judge about a statistical assessment of an implausible alibi, I was told the argument would be used to destabilise the suspect’s defence, not in court…

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