Question

Sally Clark was convicted of murdering her two babies (each of whom had been found dead in their cots) because the jury was convinced by the testimony of an expert witness for the prosecution, Sir Roy Meadow. The jury was first shown a table from the report of a government funded research team, the Confidential Enquiry into Sudden Death in Infancy. This table showed a one-in-8,543 (1/8543) risk of cot death for a baby from a family where the mother was over 26, at least one parent was employed, and neither was a smoker – a family like the Clarks. Sir Roy Meadow told the jury that to work out the risk of two cot deaths in such a family you would multiply 8,543 by 8,543 to reach a risk of one-in-73 million. With 700,000 live births a year in England, Scotland and Wales, this was an event that would happen by chance “about once every hundred years.” If you had been a member of that jury would you have been convinced by this testimony? Explain (1pt.).

Answer 1

Yes, I would have been convinced by this testimony.

Explanation-

We can model the given situation as a Binomial distribution as follows.

Suppose, X be number of sudden cot death in infancy.

As death of one child is independent of others, assuming sudden cot death during infancy as success we have,

So, probability that both of the babies died due to sudden cot death is given by

Hence, the argument given by Sir Roy Meadow is valid one.