Monday, January 9, 2017

I was talking to a math major...

Image result for five-thousandths of one percent...from Northwestern University yesterday and I asked him how to read the number .00005. (Cipherin' was never my long suit.) And the answer is: five-thousandths of one percent. Or, in English, a "rounding error."

Now, you're probably wondering where I'm going with this and suspecting somehow that I'm going to tie it in to the murder rate in Chicago. Bingo! Buy yourself a Coke. (Actually, don't; it's "no sugar January," remember?*)

But, seriously, I was thinking of this quote from a piece in the New York Times which I cited in a recent blog post (my emphasis):

The police said the shootings in those areas generally were not random, with more than 80 percent of the victims having previously been identified by the police as more susceptible because of their gang ties or past arrests.

So if 80 percent of the 762 murder victims in Chicago last year were essentially "outlaws" or "bad guys" or whatever you want to call them, then only 20 percent were "innocent." And 20 percent of 762 is 152.4, or .0000563 -- roughly five-thousandths of one percent -- out of a city of 2.7 million people. Does that sound like a significant number to you, five-thousandths of one percent? Or does it sound more like a rounding error? How many municipalities in America -- or anywhere else, for that matter -- can claim a murder rate of five-thousandths of one percent? That actually sounds pretty good to me.

(Check my math: if a city of 100,000 people has six murders in a year, that's a higher percentage than Chicago, right?)

* By the way, we're eight days into the month and I haven't had any "sugar" with the exception of what's already in the "food" I eat. That means no soda, candy, cookies, cake, pie, ice cream, etc. -- what my mom used to call "sweet stuff." And I'm reading labels now; did you know that milk has 12 grams of sugar per serving? But it's not added; it occurs naturally.

I'll have more to say about all this as the month progresses; but so far, so good.

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