Chance News 93

Quotations

“The magic of statistics cannot create information when there is none.”

Howard Wainer in Uneducated Guesses, 2011, p. 133

Submitted by Margaret Cibes

Forsooth

Ignorance is bliss, or is it?

“I remember a few years ago looking at peer rankings of graduate departments and being delighted to discover that among statistics departments my own alma mater was in the top ten (although my trust in the process was tempered by the knowledge that, despite its lofty ranking, Princeton’s statistics department had been disbanded decades earlier.)”

Howard Wainer in Uneducated Guesses, 2011, p. 141

“As they do on many obscure policy issues, Americans polarize sharply along partisan lines when they learn that President Barack Obama supports a repeal of the 1975 Public Affairs Act. …. There's one striking problem here: The 1975 Public Affairs Act does not exist. …. In a series of surveys that polled national samples about similarly fictitious or otherwise unknown legislation, [pollsters] found 20 to 40 percent of Americans were willing to offer opinions on laws they have never heard of.”

“Beware: Survey Questions About Fictional Issues Still Get Answers”, HUFFPOST, April 12, 2013

“Most uses of the classical tools of statistics have been, are, and will be, made by those who know not what they do.”

John Tukey in “The Technical Tools of Statistics”, November1964

Submitted by Margaret Cibes

Justice flunks math

Thanks to Bob Griffin, who sent a link the following op/ed:

Justice flunks math, by Liela Schneps and Caolie Colmez, New York Times, 26 March 2013

This op/ed piece is a response to the recent developments in the case of Amanda Knox (Italy’s highest court overturns acquittal of Amanda Knox, NYT, 26 March 2013). In 2009, Knox and her ex-boyfriend were convicted in Italy for the murder of Knox's roommate. The twists and turns in her prosecution have been widely documented in the media. In 2011, an appeals court overturned the convictions. But now the Court of Cassation has ordered that the case be retried.

According to Schneps and Colmez, "The Court of Cassation has not yet publicly explained the motivations behind its ruling. But the appellate judge’s failure to understand probability may well play a role." A judge has refused to order a retest of a DNA sample, recovered in 2007 from a knife in Knox's apartment, that had been tentatively linked to the victim. They continue:

Whatever concerns the judge might have had regarding the reliability of DNA tests, he demonstrated a clear mathematical fallacy: assuming that repeating the test could tell us nothing about the reliability of the original results.

Imagine, for example, that you toss a coin and it lands on heads 8 or 9 times out of 10. You might suspect that the coin is biased. Now, suppose you then toss it another 10 times and again get 8 or 9 heads. Wouldn’t that add a lot to your conviction that something’s wrong with the coin? It should.

Schneps and Colmez have collaborated on a recent book Math on Trial: How Numbers Get Used and Abused in the Courtroom, which explores misapplications of statistics in criminal trials.