back-of-the-envelope-calculations-example-homicide

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A common rhetorical ploy in policy-related public relations is the "Every seven minutes something happens" gambit. It is rather effective since it cuts right through any bias the hearer might have toward thinking a particular phenomenon is unusual just because she does not often encounter it.

While the technique is mathematically sound, it is interpretively flawed because it is completely dependent on the size of the area under consideration. A murder occurs almost never in this classroom, but in Oakland one happens every three or four days and in California about every four hours while in the US as a whole,

Example: Homicide

Intentional homicide, rate per 100,000 population, by sub-region, 2004

homicide_rate_map_web.jpg

http://www.unodc.org/unodc/en/data-and-analysis/ihs.html

http://www.unodc.org/documents/data-and-analysis/IHS-rates-05012009.pdf


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