The Story of Sally Clark Group 2 - Jing Kai (Presenter), Nabilah, Soon Guan Famous story regarding false accusation of murder and miscarriage of justice

Reading Sally Clark (5 February 2017). Retrieved 21 March 2017, from http://en.wikipedia.org/wiki/Sally_Clark The statement by Professor Dawidon: SALLY CLARK APPEAL. Retrieved from http://www.statslab.cam.ac.uk/~apd/SallyClark_report.doc The first reading is a web page depicting the story of Kelly Clark The second reading is the report regarding the appeal for Sally Clark’s conviction

Overview Background Information Conviction for Murder Analysis of Statistical Evidence Aftermath Conclusion

Background Information Born an only child in Wiltshire, South West England) Married solicitor Steve Clark (1990) Moved to Cheshire, North West England in order to practice law with her husband (1994)

Conviction for Murder Two separate incidences where Sally Clark’s baby passed away due to unknown causes (Sudden Infant Death Syndrome, SIDS) Sally Clark was found alone at home on both occasions No evidence to prove or disprove her involvement Sally Clark was convicted and sentenced to life imprisonment on 9th November, 1999 -Presence of the bacterium staphylococcus aureus in multiple sites including his cerebro-spinal fluid, indicating baby could have died due to health causes. -Conclusion based on Bayes analysis that since this probability is very low, the probability of murder is very high

The Antagonists Withheld microbiology test results for second baby Tests showed the bacterium Staphylococcus aureus in multiple sites of the baby → Baby could have died due to health concerns! Dr Alan Williams Along with the evidence (or lack thereof) presented, two other factors resulted in Clark’s miscarriage of justice. One of them is the withholding of...

The Antagonists Professor Sir Roy Meadow Bayes analysis: 1 in 73 million chance (1/8543) x (1/8543) of two children from an affluent family suffering cot death Conclusion that since this probability is very low, the probability of murder is very high The other is the statistical analysis done by Prof Roy Meadow, Professor of paediatrics at University of Leeds Based on medical knowledge and general observation of trends, he deduced using Bayes analysis that there is a 1 in 73 million of double cot death. Calculated by assuming both cases of cot death are independent. This is a highly flawed analysis and we will look into this subsequently

Analysis of Statistical Evidence Assumption of independence → Flaws in calculation: Lurking variables: Gender, genetic or environmental factors Chances of a second death increases by 5-10 fold after the first Uncertainty with probability of double cot death most likely understated Done by Prof Philip Dawid from the Royal Statistical Society, as mentioned in the second reading Previous statistical study focused on 3 pre-natal factors in families: Smokers, no waged income and mother aged below 27 at second birth. Didn’t investigate into these other variables which would affect the overall rates. Eg. Males have higher risk, 1st cot death can indicate risk of genetic predisposition and increase the risk of second child dying from cot death Backed up by extensive SID stats for England

Analysis of Statistical Evidence 2) Relevance of data: Fallacious logic Probability of double cot death Probably of innocence! (Prosecutor’s fallacy) Double cot murder is a less likely phenomenon Relative likelihood should be used Concentrates on murder as a single causation if death is not caused by SIDS. But in reality, there are many other causes up for consideration.

Relative likelihood P (2 murdered babies in a family) = 1 in 15 million P (2 SIDS deaths in a family) = 1 in 5 million P (2 SIDS deaths in a family) : P (2 murdered babies in a family) = 3 : 1 Not the real values, just illustrated as an example. But statistically speaking, it is far more unlikely for a double murder

Aftermath Unearthing of microbiological tests by Sally Clark’s husband Along with the case for flawed statistical evidence, Sally Clark was acquitted in January 2003 Review of hundreds other cases → 3 similar cases overturned Along with the help of divorce lawyer Marilyn Stowe, as they felt something fishy about the case

Aftermath Roy Meadow was struck off the medical register in 2005 for serious professional misconduct but subsequently reinstated after appeal Dr Alan Williams was banned from Home Office pathology work and coroners' cases for three years Sally Clark diagnosed with psychiatric problems associated with post- traumatic disorder and alcohol dependency syndrome → Passed away on 16th March 2007 due to acute alcohol intoxication As the nature of her conviction as a child-killer, and her background as a solicitor and daughter of a police officer made her a target for other prisoners.

Dr Sam Gulino, forensic pathologist for the State of Florida, USA. "Throughout my review, I was horrified by the shoddy fashion in which these cases were evaluated. It was clear that sound medical principles were abandoned in favour of over-simplification, over-interpretation, exclusion of relevant data and, in several instances, the imagining of non-existent findings." Dr Sam Gulino, forensic pathologist for the State of Florida, USA. Shows that the usage of statistics in the entire conviction process was highly screwed up

Conclusion Logical and accurate use of statistical information with explanations required Data needs to be precise and context- specific Failure to make appropriate inferences from statistics can result in fatal consequences This is a perfect example of statistics used wrongly. Logic can be counter intuitive sometimes, so care has to be taken

Thank You!