Chance News 24

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Quotations

Satan delights equally in statistics and in quoting scripture....

H.G. Wells, The Undying Fire.

In brief, the previous design (the two-sample comparison) had three problems: (1) not scientific, (2) not ethical, and (3) not effective. Other than that, everything was fine.

Sense and Nonsense of Statistical Inference
Chamont Wang, Page 84.

Forsooths

These Forsooths are from the Feb. 2007 RSS News.

The car poplation went up 10 per cent over the 1997-2004 period, while daily car trips more than doubled, rising 23 percent.


The Straits Times (Singapore)
24 November 2006

Online banking fraud up 8000%

The UK has seen an 8000% increase in fake internet banking scams in the past two years, the government's financial watchdog has warned...The amount stolen is still relatively small but it is set to go up by 90% for the second year running.


BBC Ceefax
213 December 2006

The danger of providing expert witness testimony when you are not an expert

Expert witness guidance: Likely implications of Professor Sir Roy Meadow’s GMC case

Sir Roy Meadow is an expert on child abuse, having published a landmark paper in 1977 on a condition known as Munchausen Syndrome by Proxy. An observation of his

one sudden infant death in a family is a tragedy, two is suspicious and three is murder, unless proven otherwise.

became knows as "Meadow's Law".

In testimony at the trial of a woman, Sally Clark, who had two children who died from SIDS, Sir Meadow tried to quantify this statement by arguing that the chances of observing two SIDS deaths would be 73 million to one. He arrived at this figure by squaring the probability of one SIDS death (8.5 thousand to one). Sally Clark was convicted of murder, but her conviction was overturned on appeal.

Dr. Meadow's testimony came under criticism, because squaring the probability only makes sense under independence. If there are genetic or environmental risk factors that influence SIDS deaths, then the probability estimate could be wrong. Not just wrong, but spectacularly wrong. It's an error that (hopefully) no statistician would make, but Dr. Meadow is not a statistician.

The General Medical Council reviewed this case and found Dr. Meadow to be guilty of serious professional misconduct and erased his name from the medical register. This action, which would prevent Dr. Meadow from practicing medicine, was still largely symbolic since Dr. Meadow is currently retired from medical practice.

Dr. Meadows appealed this decision in the British Courts which ruled that the actions of the General Medical Council should be overturned because expert witnesses will refuse to testify if they believe that their testimony, if shown later to be invalid, could lead to sanctions.

Questions

1. What is the proper course of action if an expert witness is asked questions outside his/her area of expertise?

2. Do Sir Meadow's actions constitute an honest mistake or serious professional misconduct?

3. Do expert witnesses need immunity from recrimination if their testimony is found to be in error?

Additional readings

(1) Royal Statistical Society, [RSS%20Statement%20regarding%20statistical%20issues%20in%20the%20Sally%20Clark%20case,%20October%2023rd%202001.pdf Statement regarding statiscal issues in the Sally Clark case,
Press Release, October 23, 201.

(2) Ray Hill, Multiple suddent infant deaths--coicidence or beyond coicidence?, Paediatric and Perinatal Epidemiology, 18 (2004), 320-326.