31 Oct 2009 11:53
[Corrected 1 Nov 2009]
In most of North America, Daylight Saving Time ends early tomorrow morning. You know the drill: when the clock strikes
3:00 2:00 AM tonight, turn it back to 2:00 1:00 AM. (Just once. At 3:00 2:00 the second time, leave it alone.) If you’re in Newfoundland, however, you have a lot more work to do. You flip your calendar to November, wait one minute, flip it back to October (and turn your clock back), wait 59 minutes, then turn it to November again. I’m not kidding. Daylight saving time in Newfoundland ends at 12:01 AM (which occurs at 10:31 PM my time), not at 3:00 AM like everywhere else.
As far as I know, this is the only place on the planet where the day of the week (and this year, the month, too) ever goes backwards. Hasta ayer!
Instructions Turn your calendar forward to November 2009 right after 11:59:59 PM on October 31, 2009. November 2009 (first time) lasts for one minute (red line), until 12:01 AM (Daylight Saving Time). At 12:01 AM on November 1, 2009, set your clock back an hour and also turn your calendar back a month, to October 2009. October 2009 then resumes for another 59 minutes (shaded box), until 12:00 AM (Standard Time) on November 1, 2009. Then turn your calendar forward to November and go to sleep.
[Added 1 Nov 2009] Thanks to my brother for pointing out that DST ends at 2:00 AM, not 3:00 AM. FWIW, I wasn’t the only one to think DST ended at 3:00. The TV listings at titantv.com showed the change an hour late also.
29 Oct 2009 16:41
No, it’s not another Philip Glass premiere, but that was a good guess. The correct answer is The Kinks Choral Collection.
I’d love to see my friends come hear me in either or both Dessoff gigs I’m part of this month:
If you can’t make it to one of our shows, you’re not off the hook:
- November 18th: Dessoff appears on The Late Show with David Letterman. A small group of Dessoff singers (not including me) will back up Ray Davies, who’ll be Dave’s guest that day.
28 Oct 2009 22:56
Posted by Steve under News
, Statistics1 Comment
Kevin Underhill* emailed me today about the Schwarzenegger veto letter. Specifically, Kevin wondered whether “it might be possible to calculate the odds against this arrangement of letters being entirely random, as the Governor’s office has claimed.”
Kevin wasn’t the only one to wonder about the odds and contact a math professor.
Several hours after Kevin wrote me, SFweekly.com published “Odds Schwarzenegger’s ‘I F–k You’ Message Was Coincidental? About One in Two Billion, Says Math Prof.” SFweekly.com quoted Stephen Devlin, a mathematician at University of San Francisco, and Gregory McColm, a mathematician at the University of South Florida, and printed various tiny chances, including a) 1 in 10 million, b) 1 in 100 million, and c) 1 in 2 billion. These are (using rough estimates of initial-letter frequencies in English words) the chances a) that seven randomly selected lines of English text begin with f, u, c, k, y, o, and u, in that order, b) that eight randomly selected lines of English text begin with i, f, u, c, k, y, o, and u, in that order, and c) that the first letters of eight randomly selected lines of English text and two blank lines separating those lines into three groups appear in the sequence i, blank, f, u, c, k, blank, y, o, u. The chances of c) are 1 in 2.1 billion, by my calculation, but no matter—only the order of magnitude is of interest here.
Whether many visitors to SFweekly.com (well, male ones of any persuasion) read the piece is questionable. It appeared next to two photo links with more click appeal than “Blah Blah F–k Blah Blah Math Prof.”: Exotic Erotic Ball (image of exotically costumed ladies kissing) and San Franciso’s Hottest Chefs (image of boyish chef wearing five o’clock shadow and a uniform, smiling seductively).
Similar calculations appear with less distraction elsewhere.
For the record, even before making any calculations, I was convinced beyond a reasonable doubt that the governor meant full well to say “fuck you.” In a later blog post, however, I’ll try to explain that the unlikelihood of “fuck you” or “i fuck you” appearing in a letter isn’t in and of itself a smoking gun.
*I’ve e-known Kevin for a couple of months now, ever since I introduced myself with an unceremonious, if politely worded email to the effect of “your arithmetic is wrong.” More details here. It turns out to be a better way to meet people that you might think.
Kevin finds fortune at Shook, Hardy, and Bacon (shb.com, Alexa US traffic rank 292,302, with 132 sites linking in), and he finds fame at Lowering the Bar (www.loweringthebar.net, Alexa US traffic rank 59,588, with 145 sites linking in).
20 Oct 2009 17:30
The following subheadline on the Scientific American website caught my eye today (and not only because of the missing period):
New research makes the case for hard tests, and suggests an unusual technique that anyone can use to learn
I may be a bit thick, because neither the article nor the research paper it mentioned suggested any unusual technique to me. But this was better than my last wild goose chase reading episode, when I vainly sought a footnote on a cereal box (there was a dagger: †, but no footnote. Can you believe that?).
Henry Roediger and Bridgid Finn, the Scientific American article’s authors, write that researchers Kornell, Hays, and Bjork found that “learning becomes better if conditions are arranged so that students make errors.” There’s that pesky word “better.” Better than what? The eternal unanswered question. My guess is that Scientific American is reporting that Kornell et al. have found that learning under a) conditions arranged so that students make errors is better than learning under b) conditions arranged so that students do not make errors. In other words, that the researchers found errorful learning to be better than errorless learning. Not that it’s a bad article, but it would be nice if Roediger and Finn had stated what they’re reporting a bit more clearly. (This is why I give writing assignments to my statistics students. By the end of the semester, they better learn not to use adjectives like better without answering “Better than what?”.)
Anyway, Kornell et al. do mention errorless learning in their paper, recently published in the Journal of Experimental Psychology: Learning, Memory and Cognition® (yes, the name of the journal is a registered trademark), but they don’t study it. The abstract notes that they examine the question of “what happens when one cannot answer a test question—does an unsuccessful retrieval attempt impede future learning or enhance it?” Kornell et al. didn’t exactly examine this question either, because they didn’t (and possibly couldn’t) isolate what part of the learning in their scenario was “future” learning. In addition, they only studied learning after wrong answers, so one must be careful not to assume their research sheds light on getting test questions wrong vs. getting them right. (Suppose a researcher reported that “Student learning among African-Americans is enhanced when they are given test questions they cannot answer.” If the researcher only studied African-Americans and made no comparison to other populations, the reported finding might easily be misinterpreted.)
What Kornell et al. did was compare two scenarios for learning previously unknown information. One scenario was unsuccessful retrieval attempts (the students were asked to provide the not-yet-learned information as answers to test questions, and they answered incorrectly). In this scenario, the retrieval attempt was followed by feedback that included a brief presentation of the new information (i.e., the correct test question answer). The second scenario was a longer-lasting presentation of the new information with no retrieval attempt (the students were not asked to answer a test question, and it’s unclear in some of the experiments whether the students knew what kind of test question they would later be asked). Not surprisingly, unsuccessful retrieval attempts enhanced learning (as measured by scores on a test containing questions like those in the retrieval attempt), when compared to presentation of new information with no retrieval attempts. Despite the Scientific American article’s subheadline, this research makes no case that “hard tests” are better for learning than non-hard tests. They may be, but this research doesn’t help us figure it out. The research does support the value of tests, hard or not-hard, so long as there’s feedback with the right answer.
8 Oct 2009 1:58
Almost every semester, I use the AOL Breach data as a point of departure for something in at least one of my classes. The data is fascinating. Most data is fascinating, but this data is particularly so: at once shocking, funny, creepy, poignant, sad, frightening, noble, ignoble, shrewd, and lewd. It’s also rich in the way data can be rich. It’s completeness—for a sample of several thousand AOL accounts, it includes the complete account search history during March, April, and May of 2006—which includes timestamped search strings and the result rank and destination of clicks-through, makes it ripe for discovering all sorts of patterns of human thought and behavior.
It’s AOL data week in one of my classes now. This morning, I proposed several nontrivial questions about the data that could be answered with SQL queries. We looked at the results and discussed what they might say about the unwitting study subjects. Then I asked my students to suggest some questions of their own. What are the typical time-of-day and day-of-week patterns of an individual AOL customer’s searches? Are there identifiable differences in the patterns (and by extension in the sleep, social, and perhaps employment or school behavior) of people whose searches included, say, “britney”? For what kinds of searches do users most often click through several pages of results? And so on.
One of my students suggested an excellent simple question. What are the most common searches of the form “how to …”? Out of millions of queries in the AOL data, there were many thousands of “how to … ?” searches. The most frequent was “how to tie a tie,” requested 92 times by a total of 47 distinct users. The rest of the top ten (in terms of most distinct users asking the question) were how to write a resume, gain weight, have sex, get pregnant, write a book, write a bibliography, start a business, lose weight, and make money, each sought by a dozen or more different people. AOL converted the queries to lower case and removed much of the punctuation, but they didn’t correct spelling. Consequently, how to masterbate and how to masturbate appear separately at ranks 49 and 51 respectively. The question would have nearly hit the top 10 without the misspellings.
Here’s a PDF file of the top 1000 “how to” queries submitted through AOL explorer by a sample of AOL users in the spring of 2006. You can probably guess that it’s not safe for work. Although there are no pictures, plenty of sex, drugs, and gambling is spelled out, and there are more than a few questions likely to offend in one way or another. Have a look.