A statistics expert says the odds are better of dying in a car accident, than being killed by random crime.
January 19, 2008
Paola Loriggio
Staff Reporter
As long as there have been cities, there has been fear. Fear of violence, fear of death, fear of anonymous, big-city crime.
High-profile cases of random crime – like the recent shootings of John O'Keefe and Hou Chang Mao, both innocent bystanders killed within a week – feed the public's anxieties.
But is that fear justified? Random crime isn't going away, but neither is it increasing. Does a spate of random killings put us in greater danger than before? The Star asked an expert statistician to assess the risk.
University of Toronto professor Jeffrey S. Rosenthal is the author of Struck by Lightning: The Curious World of Probabilities, a book about probability and randomness in everyday life.
Q: For the average Torontonian, what are the odds of getting killed in a random crime, like, say, a stray bullet?
A: In Toronto, about 12 people per year are killed by a stranger. There are 2.6 million people in the city, so your chances of getting killed by a stranger are about one in 220,000.
So, not very likely at all.
Q: How do you calculate that?
A: We work in terms of statistics for recent times, like the number of homicides per year. In 2007, there were 84 homicides in Toronto. (It usually goes from 60 to about 80.)
There are also statistics on the victim-offender relationship. Only about 15 per cent (of victims) are killed by a stranger. So 15 per cent of 80 homicides ...
In comparison, your chances of getting killed by your spouse are one in 135,000, or about 50 per cent higher.
Q: What else can you compare it to?
A: In Canada, one out of 440 people dies of cardiovascular disease, 125 times more likely than getting killed by a stranger.
About 3,000 Canadians die in car accidents each year, so nationally, the odds are one in 11,000 – 20 times more likely.
But people worry a lot more about getting killed, when in reality, they should worry about car accidents.
Q: Do individual behaviours or characteristics affect the risk of getting killed?
A: There are variations for personal lifestyle and habits, but it's difficult to calculate.
Obviously, if you hang out in nightclubs a lot or you live in a (dangerous) neighbourhood ... your odds increase – or if you have a job that takes you into dangerous situations, like a police officer.
Q: If the odds are low, why does the public still worry more after high-profile homicides?
A: I call that "headline bias" – when something makes the news, people think it happens a lot. But the reason something makes the headlines is because it doesn't happen a lot.
To my mind, public reaction is not in co-ordination with the actual statistics.
Toronto is actually quite a safe city, better than most American and Canadian cities. And the level of violent crime has stayed pretty steady over the past few years.
A few homicides close together doesn't necessarily mean crime is going up. Sometimes, gang-related incidents can be related – like, today's shooting is retribution for the one that happened yesterday – but that's not true of everything.
Q: What causes that public reaction?
A: For headline bias, I have a theory about why it happens.
Our brains evolved when we lived in smaller groups, with less access to information.
So if you heard that someone was eaten by a lion, it was probably one of the 50 people in your tribe. It meant there was a lion around and you should be careful.
Today, if you see a headline about someone getting shot, it's one person out of 5 million (in the GTA), and it doesn't mean there's any greater risk to you.
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