Power-law distribution, homelessness and cars

I, uh, e-mailed this article to a couple social science friends to see what they make of it. It's a very good piece on tax hawks and civil libertarians. It deals with a lot of situations that are not similar (to me), but the author elegantly weaves an argument. A lot of these situations are experienced in every major cities, so read on.

Fifteen years ago, after the Rodney King beating, the Los Angeles Police Department was in crisis. It was accused of racial insensitivity and ill discipline and violence, and the assumption was that those problems had spread broadly throughout the rank and file. In the language of statisticians, it was thought that L.A.P.D.’s troubles had a “normal” distribution—that if you graphed them the result would look like a bell curve, with a small number of officers at one end of the curve, a small number at the other end, and the bulk of the problem situated in the middle. The bell-curve assumption has become so much a part of our mental architecture that we tend to use it to organize experience automatically.[...]

In the nineteen-eighties, when homelessness first surfaced as a national issue, the assumption was that the problem fit a normal distribution: that the vast majority of the homeless were in the same state of semi-permanent distress. It was an assumption that bred despair: if there were so many homeless, with so many problems, what could be done to help them? Then, fifteen years ago, a young Boston College graduate student named Dennis Culhane lived in a shelter in Philadelphia for seven weeks as part of the research for his dissertation. A few months later he went back, and was surprised to discover that he couldn’t find any of the people he had recently spent so much time with. “It made me realize that most of these people were getting on with their own lives,” he said. [...]

In Stedman’s view, the current system of smog checks makes little sense. A million motorists in Denver have to go to an emissions center every year—take time from work, wait in line, pay fifteen or twenty-five dollars—for a test that more than ninety per cent of them don’t need. “Not everybody gets tested for breast cancer,” Stedman says. “Not everybody takes an AIDS test.” On-site smog checks, furthermore, do a pretty bad job of finding and fixing the few outliers. Car enthusiasts—with high-powered, high-polluting sports cars—have been known to drop a clean engine into their car on the day they get it tested. Others register their car in a faraway town without emissions testing or arrive at the test site “hot”—having just come off hard driving on the freeway—which is a good way to make a dirty engine appear to be clean. Still others randomly pass the test when they shouldn’t, because dirty engines are highly variable and sometimes burn cleanly for short durations. There is little evidence, Stedman says, that the city’s regime of inspections makes any difference in air quality.

The journalist, Malcolm Gladwell, also writes bestseller books: The Tipping Point: How Little Things Can Make a Big Difference and Blink: The Power of Thinking Without Thinking.