Driving Risk

I’m continually wondering about the risks involved in the outdoor activities I love. I probably won’t ever get a clear answer for most of them, because most have too many variables and too little data available. Still, I keep coming back to the questions. Shouldn’t it be possible to at least come up with a pie-in-the-sky guess at the degree of risk inherent in an activity? I don’t know, but I do know one thing I would need first: a basis of comparison. My impulse is always to compare outdoor risks with the risk of an activity nearly everyone participates in, driving. So today made my way to the National Center for Statistics and Analysis, and downloaded the 2004 Traffic Safety Facts Annual Report.

My first question is, what is the risk of dying inherent in the activity? Clearly we need to know the number of participants and the number of fatalities associated with the activity to answer this. For driving, there’s another place to answer this question, the the Odds of Dying (2002) page at National Safety Council. For that year, the odds of a “car occupant” dying were 1 in 17,625. Doing the same calculation for 2004 from NCSA report, the odds that year were 1 in 8,862. Wow, is driving getting much more risky? It turns out 2002 was a record low year for auto fatalities in the US. Maybe we should look at a few years, using prior NCSA reports and US population estimates:

Year Odds of dying as a car occupant
1992 1 in 7755
1993 1 in 7677
1994 1 in 7584
1995 1 in 7445
1996 1 in 7429
1997 1 in 7494
1998 1 in 7639
1999 1 in 7604
2000 1 in 7573
2001 1 in 7623
2002 1 in 7528

Wow, much different results for 2002 that way. An illustration, I guess, that risk estimates will vary wildly even with loads of data. There’s also an assumption here that the entire US population are “car occupants” at some point – seems likely enough for this guesswork. Even if the real risk is half, or twice this estimate, at least we have something.

It would also be nice to do some numbers for injuries, not just fatalities. Scanning the reports, I can see that numbers for injuries are even sloppier than for fatalities. I can see that the odds of injuries appear to be declining since 1996, so let’s take the low number and say there are about 75 injuries for every fatality. If we estimate the risk of dying in a car as 1 in 8,000, the risk of injury would be 1 in 106.

Now I would like to take these numbers and do some guessing about what the odds are for other activites, but that’s for another leisurely morning…

8 responses to “Driving Risk”

  1. I’m guessing that all this risk estimation might be partly inspired by the NYTimes article I emailed you–was it yesterday?–about the risk of avalanches. I actually was inspired to email that article because of your blog about your avalanche class.

    Despite being your mother, I actually don’t worry too much about what appears risky that you do. I’ve always assumed that the actual statistics are probably pretty low compared, as you point out, to driving. I also don’t worry much about flying, as I figure it’s a lot safer than driving, which I already have been doing for close to fifty years and I’m still here.

    I try not to run my life by the “what ifs.” There are, of course, sensible what ifs to be considered, but after the obvious precautions, seems to me you oughta go for it, baby! After all, hiding under the bed might just kill you with dust mites.

  2. Yes, the avalanche class and your email were reminders, but the seed was planted when I was hiking alone in Glacier National Park, wondering what the real risk of a Grizzly attack was. Even after making it through without a Grizzly sighting, I wondered what odds I had bucked. I’ve been mulling this over for a while, and this gives me a starting point for further investigations…

  3. There’s a book called Innumeracy by a math professor at Harvard or, and in the book he talks about a logarthamic risk scale. It was required reading, so I didn’t catch much of it, but it seems like you could use it.

  4. It is easy to find data on deaths for car accidents-it seems you found quite a bit (maybe almost too much!?!

    Try finding information about the distribution of income for folks making 75K+ or more every year.

    There is a lot of data available about the poor people in this country but it was very hard (with the 2 hours of online searching I did) to find anything on wealth distribution for the “rich”…the best I could find was data from 2003 gov. study which said that 12.8 percent of the 100,000 people they surveyed (15 years and older) made over 75K a year.

    But-it did not give a breakdown of this upper tail. Basically, what my officemate and I wanted to know was-what constitutes “rich” these days? How many “rich” people are there in the US? And, also, how do the US “richies” compare to other countries? GOOD LUCK (or maybe I don’t know what I’m doing when I’m searching)!

    I was having a discussion with an officemate about the distribution of incomes, when we came to the conclusion that we just have no idea how the wealth is distributed in this country…with the exception of the poor as they are very well documented!


  5. Ha! Just few days ago I was talking with my friends, and I said “frankly, I think out of all the activities I do, driving is the most dangerous one.”

    It’s nice to hear another outdoor person has similar thoughts!

  6. Thanks Dude for the list of references…I will be *sure* to check them out!

    Have you looked into morbidity rates of bicyclists? My Dad for many years commuted to work using a bike (like you), and he had treacherous commutes more than once (dog bitings, muddy patches, vehicle collisions!).

    I think that scares me the most when I’m riding…vehicles that is!


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