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Counting lessons

Michelle Goldberg, stalwart of Salon.com’s anti-war beat, wrote an article (available if you watch a short ad) about how the hell one estimates crowd size. Interviewing a sociology professor:

McPhail says … eyeball estimates are usually wrong. The crowd-counting method he uses, he says, was devised by Berkeley journalism professor Herbert Jacobs in the 1960s during the Free Speech movement. Sproul Plaza, where the protests were held, was made of concrete poured in uniform sections. By measuring the sections, estimating the crowd density and counting how many sections were filled, Jacobs was able to come up with fairly reliable numbers. Farouk El-Baz, director of the Center for Remote Sensing at Boston University, says that the methodology is well known and well respected by scientists.

What about Jan. 18?

The counting formula divides the mall into eight panels and measures the square footage of each. For really huge protests, aerial photographs are necessary to determine how much space is occupied, but Saturday’s rally was small enough that McPhail and another professor, John McCarthy of Pennsylvania State, could easily walk through the gathering many times, noting its borders and its density.
A crowd of 500,000, he says, would have filled all eight panels, stretching from the Capitol Building to the Lincoln Memorial, or from Third Street to 14th Street. Saturday’s protest, he says, filled only one and a quarter panel, and only a fraction of that was densely packed.

So how many people were in D.C.? About 55,000.

Sort of makes this look stupid. Oh, wait – it already was.

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