I talked about making sense of statistical data in general a while back. Recently, the latest issue of Nature ( vol. 445, no. 7125, p. 254-255 [electronic version requires subscription]) features a story of how statistics has been used and interpreted in court house. I guess the author, Mark Buchanan, intended to remind to beware of the use of statistics outside scientific arena. In social setting, nothing can be controlled as in an experiment room. Context is crucially needed. He introduced two particular cases. The first one is suspected nurse who may have killed her patients. The second one is a mother who has been suspected of killing her two daughters. Both cases involved the probability of the chances that suspects could have committed murders.
Two points mentioned in the paper are standing out. For the nurse’s case, the statistician told that “the chance that her presence was mere coincidence was only 1 to 342 million”. Well that seems very impossible, right? But the mathematician said by brining additional independent variable – include more factors – the chance could be as small as 1 in 48 or 1 in 5. My question is which number seems possible for most of us then. At what level of chance that you can say that could not be coincidence anymore?
Another point is from the quote below.
[L]awyers have an incentive, and even a duty, to select the evidence that makes their case stronger. “What the judge ends up hearing often comes from the two extreme ends of the distribution,” he (David Kaye) said.
I think the use of statistics is very outstanding example of how people make sense of “number” is very influential and does affect the way we live.
Inside this issue of Nature (p.249), there is a article about Apple Inc. has been sued by its shareholder about backdating stock options. They already confessed and Jobs knows about it.