Friday, October 9, 2015

DNA Statistics Under Review

We really really have to pay attention to forensic sciences in criminal cases.  While I have focused on arson, handwriting and presently abusive head trauma; I can sense that the protocol for matching in DNA cases along with the underlying statistics will make that arena a future battleground.  The recent issue of Atlantic magazine has brought the future to the present.  See:

The article starts by noting:

In 2001, an analyst in the DNA unit of Arizona’s state crime laboratory noticed something interesting. Two seemingly unrelated individuals—one white and one black—shared the same two markers at nine of the 13 places in the standard DNA profile. Yet that particular genetic profile should have been exceedingly rare.
According to the standard method of computing how often one might expect to encounter a particular DNA profile in the population at large—what is known as the “random match probability”—if you plucked a non-Hispanic white person at random from the population, there would be only a 1 in 754 million chance of finding that profile. For African Americans, the number was 1 in 561 billion. And yet here, in a database of less than 100,000 people, it was appearing twice—and in people of different races.

Here we go.  The future is now!