Chance News 96

Quotations

"The world is a messy place. The scientific method imposes some order, but in the case of climate change, that order is probabilistic. For the sake of science and the planet, we should not become distracted by a false sense of certitude. Imprecise truths are the most inconvenient ones."

Gernot Wagner and Martin L. Weitzman, in: Inconvenient uncertainties, New York Times, 10 October 2013

Submitted by Bill Peterson

Let's make an XKCD

Thanks to Brian Abend for sending a link to this cartoon from XKCD

The Monty Hall problem just won't stay solved, so it was only a matter of time before it was enshrined in XKCD. Here's another recent appearance in the news:

Stick or switch? Probability and the Monty Hall problem, BBC News Magazine, 11 September 2013

Corrupt Ivy League admissions?

Writing last year, in the American Conservative (The myth of American meritocracy: How corrupt are Ivy League admissions?, 28 November 2012) Rob Unz claimed that today's Asian students were now being discriminated against in ways that Jewish students had been in the past. Namely, despite growing numbers in the population and impressive academic accomplishments, their share of the admissions to top institutions was being restricted by quotas. Furthermore, Unz went on to assert that Jewish students are now actually over-represented relative to equally qualified Asians and non-Jewish whites. Unz's article includes various statistical graphics to support these claims; for example, see

At the time of the article, a blog post by Andrew Gelman took the analysis at face value and asked, Should Harvard start admitting kids at random? (28 November 2012). Subsequently, however, Gelman and others were led to re-examine the Unz data, and found that many of the earlier claims do not stand up. For example, instead of inferring Jewishness via a family name, Janet Mertz actually contacted some of the individuals who were on the Math Olympiad team. She writes here that

The actual count of Jews is at least 10¼ out of 78 (counting part-Jews fractionally), i.e., 5-fold higher [than Unz's claim of only two ]. When an author refuses to admit to an error about which there is no possibility he is correct, academics have no choice but to then question the validity of everything that author has ever written because they can no longer trust the veracity of his statements.

Most recently, in a post entitled Ivy Jew update (22 October 2013), Gelman quotes Nurit Baytch:

Unz’s conclusion that Jews are over-admitted to Harvard was erroneous, as he relied on faulty assumptions and spurious data: Unz substantially overestimated the percentage of Jews at Harvard while grossly underestimating the percentage of Jews among high academic achievers.

This latest post by Gelman has a number of interesting quotations, that are worth bearing in mind when looking at any statistical claim:

• "My take on all this is that it can be harder than it looks to do research using statistics."
• "It’s perfectly natural to get excited when one’s initial hypothesis is confirmed by an examination of some data, but the next step is to recognize that these exciting discoveries do not always hold up."

Regarding the particular analysis in question, he writes

Unz, who spends so much of his time in the political arena, is used to politically-motivated criticisms and responds in kind, and so I think he sees the statistics provided by Mertz and Baytch as attacks to be dodged or parried rather than as useful information that can help him modify his understanding of the world. But for those of us how are not so invested in a particular position, Baytch’s article, and Mertz’s from a few months ago, should be helpful to anyone interested in further study of ethnicity and high-end college admissions.

In a related post, My beef with Brooks: the alternative to “good statistics” is not “no statistics,” it’s “bad statistics” (20 February 2013), Gelman takes columnist David Brooks to task for adopting an "anti-data" posture in a NYT column. He observes that Brooks had previously been happy to quote the Unz analysis in a column two months earlier. According to Gelman, "Janet Mertz contacted him and the Times to report that his published numbers were in error, and I also contacted Brooks (both directly and through an intermediary). But no correction has appeared."

Submitted by Paul Alper

Dance of the p-values

Paul Alper sent a link to a wonderful YouTube video, Dance of the p-values. This is an animated simulation--with sound effects keyed to emotional responses--designed to show how erratically the p-value varies in replications of the same experiment.

The video has also drawn recent discussion on the Isolated Statisticians e-mail list. Paul found it through Andrew Gelman's blog (7 November) which also features this cartoon: