Chance News 80

Weirdness?

Why People Believe Weird Things: Pseudo-Science, Superstition, and Other Confusions of Our Time
by Michael Shermer, MIF Books, 1997, p. 54

Shermer is founding publisher of Skeptic magazine and a Scientific American columnist. This book contains his list of “Twenty-five Fallacies That Lead Us to Believe Weird Things.” The fallacies are not new, but are well illustrated by many interesting historic and contemporary stories.

See Shermer's 13-minute TED Talk[1], including a demonstration of a $900 “dowser” designed to find marijuana in kids’ lockers. Shermer states:

Science is not a thing, it’s a verb. It’s a way of thinking about things. It’s a way of looking for natural explanations for all phenomena.

Question

Shermer states:

[M]ost people have a very poor understanding of the laws of probability. …. The probability that two people in a room of thirty people will have the same birthday is .71.

Ignoring issues such as leap years or twins, and assuming a uniform distribution of real-life birthdays, do you agree with the probability as stated – or could you modify the statement to make it more accurate?

Submitted by Margaret Cibes

Improving IQs

“Ways to Inflate Your IQ”
by Sue Shellenbarger, The Wall Street Journal, November 29, 2011

This is a report about a potpourri of research projects that claim to show that an IQ can change over time. Some sample IQ test questions, with suggestions about how to increase an IQ, are also provided. There is no discussion about what an IQ test measures.

In the latest study, 33 British students were given IQ tests and brain scans at ages 12 to 16 and again about four years later …; 9% of the students showed a significant change of 15 points or more in IQ scores.
On a scale where 90 to 110 is considered average, one student's IQ rose 21 points to 128 from 107, lifting the student from the 68th percentile to the 97th compared with others the same age, [according to a co-author] of the study, published last month in Nature.

According to a 1999 National Institutes of Health study over 30 years, people with complex jobs have increasing IQs and those with simpler jobs have decreasing IQs.

Questions

1. We are told that 33 British students took an IQ test twice. It is conceivable that there were additional students who participated in the first test administration but not the second. Would it be helpful, for inference purposes, to have information about any such students, such as reasons for their non-participation in the second administration?
2. When people are IQ tested over time, do you think that they are given the same test (or a parallel version), or might a subsequent test include different skills/concepts appropriate for an older group?
3. On one commonly used IQ test, scores are standardized to mean 100 and standard deviation 15. This is consistent with the claim that a 107 score rising to 128 corresponds to a 68th percentile score rising to the 97th. How would you equate the test scores from two administrations if the tests were different? (See “Equating Test Scores”,”by Samuel Livingston, Educational Testing Service, 2004.

Submitted by Margaret Cibes