04 October 2007

Too Convenient

In today's news, police reported that 80% of crimes are committed by locals, and only 20% by foreigners. This seems to me like an over-convenient application of the 80/20 rule, with no hard numbers quoted in the news item at all.

So I decided to put on my armchair economist hat and do some simple calculations to determine if we actually have more to fear from locals.

The number of crimes reported to the police (consisting of violent crime and property crime) (2004): 156,315
80% of that would be... 125,052, while
20% would be... 31,263

The number of legal foreign workers (2003): 1.1m
The number of illegal foreign workers (2005): 1.2m
So the estimated number of foreigners in the country is about 2.3 million.

The number of locals over 18 (2005): 15.7m

So... 125,052 crimes are committed by locals (15.7m) while 31,263 crimes are committed by foreigners (2.3m). If we assume that a crime is only committed by one person and the criminal only does it once, that would mean:

0.796% of locals are criminals, and
1.359% of foreigners are criminals (almost double!)

In other words, though the percentage is small, a foreigner is twice as likely to be criminally-inclined compared to a local. That's worrisome enough!

So in fact we *still* have more to fear from foreigners than locals, but not as much as I initially thought. There are a LOT of caveats to the numbers I used, so don't go quoting my page in any research paper you're doing.

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