January 08, 2004
Statistical Innumeracy

Mark Kleiman bangs his head against the wall in frustration at reporters who have no understanding of statistics: Mark A. R. Kleiman: Wrong!: WASHINGTON -- Wesley Clark has closed the gap with Howard Dean among Democratic voters, according to a national poll taken at a time when Dean had been under intense criticism from rivals. Dean had the support of 24 percent and Clark had the backing of 20 percent in the CNN-USA Today-Gallup poll out today. The poll of 465 Democrats and those who lean Democratic had a margin of sampling error of plus or minus 5 percentage points, meaning Dean and Clark are essentially tied for the lead nationally. No, dammit, no! [Pounds the lectern in sheer frustration.] Being 4 points behind with a 5- point margin of error isn't being "essentially tied." It's being 4 points behind, plus or minus 5 points. That's a lot better than being 21 points behind, plus or minus 5 points, but I'd rather be ahead, thanks. Of course, the reported margin of error reflects sampling error only, and ignores all the sources of systematicerror. All it means is that, if I'd called another 465 people at the same time, using the...

Posted by DeLong at 11:55 AM

July 26, 2003
Yes, Virginia, There Is a Law of Large Numbers

All those who believed William Bennett--and disbelieved the law of large numbers--when he claimed he had come out "close to even" in his gambling need to mark their beliefs to market: Las Vegas SUN: Bennett Admits Losing 'A Lot of Money': WASHINGTON (AP) - Family values advocate William Bennett rejects reports that he lost $8 million at casinos over 10 years but acknowledged it was "a lot of money." "Maybe not too much, given what I made, but too much given who I am and what I do," the former education secretary said. "I think it was just best to call it quits." In an interview to be aired Saturday on CNBC's "Tim Russert" show, Bennett said he was never a gambling addict, and that his history of betting shouldn't diminish his credibility.... "It was a high level, was a lot of money," he said, and "counting up, has made a difference in our lives."... The Las Vegas Sun does not consider the effect on Bennett's credibility of previous claims to have come out "close to even"......

Posted by DeLong at 06:08 PM

May 24, 2003
Elementary Trigonometry

The sun crosses the heavens at a rate of 15 degrees per hour... That's pi/12 radians per hour--or 0.25 radians per hour... The western backdrop to Berkeley's Greek Theater is some 40 feet tall... It's 2 P.M., but let's make things simple and assume that it's noon--when d(tan(theta))/d(theta) = 1--the foot of the shadow cast by the backdrop moves west at a rate of d(tan(theta))/d(theta) x (pi/12) = 10 feet/hour... Because it's not noon but 2 P.M., d(tan(theta))/d(theta) is not 1 but is instead... 1 1/3... The leading edge of the shadow is still 4 feet away. 20 more minutes and I'll be in the shade......

Posted by DeLong at 07:49 AM

May 10, 2003
We Should Vacation in Crete

The Ten-Year-Old: Dad? Me: Yes? The Ten-Year-Old: I know a question, the answer to which is either "yes" or "no," that you cannot answer correctly. Me: And the question is? The Ten-Year-Old: Are you going to answer this question with a "no"? Me: [Pause] Aha. The Ten-Year-Old: I didn't think of it myself......

Posted by DeLong at 04:48 PM