Our latest Freakonomics Radio on Marketplace podcast is called “The Season of Death.” The gist: Summertime brings far too many fatal accidents. But the numbers may surprise you.
If you’re a longtime reader, you probably already have an idea of what we’re talking about. Human beings are, in general, quite bad at assessing risk. We tend to be scared of big, noisy, anomalous events – like shark attacks, which in an average year kill fewer than five people worldwide — while overlooking the seemingly quotidian reality of, say, drowning deaths (about 4,000 per year in the U.S. alone) and motorcycle fatalities (about 4,500 U.S. deaths annually). We have been exploring this idea since Freakonomics, where we asked whether a gun or a swimming pool is more “dangerous.”
In the podcast, we look into the death rate from four popular summertime activities: motorcycling, swimming, boating, and skydiving. Comparing such rates is rarely an apples-to-apples proposition but we do our best to sketch out the relative danger of each. You’ll hear from:
- Randa Radwan Samaha, director of advanced research at the National Crash Analysis Center, which tracks motorcycle accidents;
- Julie Gilchrist, a medical epidemiologist at the Centers for Disease Control and Prevention, which catalogs drowning deaths and the many other ways in which Americans die;
- Mike Baron of the U.S. Coast Guard, which keeps a tally of recreational boating deaths; and
- Nancy Koreen of the U.S. Parachute Association, which maintains a detailed online accident report. Koreen tells us that skydiving fatalities average about 22 per year, or 7 per 1 million dives, and that most fatalities are among experienced divers trying a difficult maneuver or watching out for their students — like these two instructors, who had 22,000 jumps between them. (Thanks to Jordan Pine for pointing us in this interesting direction, and for Kevin Boland for seconding the motion.)
Along we way, we ran across an interesting wrinkle in the motorcycle data. Take a look at this table from a National Highway Traffic Safety Administration report and see if you spot something hinky:
First of all, look at the massive spike in registered vehicles — from 4.9 million in 2001 to 8.2 million in 2010. We were told this was due in part to heavy marketing to (and purchases by) aging baby boomers reconnecting with their easy riding youth. Maybe, but still, that’s a big increase.
Then look at how the fatality rate increases significantly from 2001 to 2006. That could certainly fit the aging-boomer story. But then, thankfully, the fatality rate absolutely plunges — from 40.14 per 100 million vehicle miles traveled (VMT) in 2006 to 24.18 in 2007.
What happened? Did all those aging boomers with sub-par eyesight and reflexes decide en masse to keep their bikes in the garage?
Apparently not. Look at how the motorcycle miles driven suddenly went through the roof that same year, from 12 billion in 2006 to 21.4 billion in 2007. Such a huge and sudden spike in miles driven can of course explain how death rate plummeted (even while the number of deaths rose by 337), but it also makes you wonder if these statistics are at all trustworthy.
Randa Samaha from the National Crash Analysis Center told us that motorcycle usage and crash data are widely understood to be imperfect. In recent years there have been adjustments in how those data are gathered, leading to radically different statistics. Consider this recent Transportation Research Board report:
“There appears to be no uniformity of motorcycle VMT estimation method among the states, and no validation of the accuracy of various methods … For example, VMT estimates showed little fluctuation from 1982 – 2002, even though in the mid-1990s motorcycle registrations and fatalities dropped to approximately two-thirds of their 1982 levels. Motorcycle VMT estimates declined 10% between 1999-2002, even as motorcycle registrations increased by 20%, sales of new motorcycles soared by 63%, and motorcycle fatalities rose by 68%.”
So it’s possible that motorcycle riding is a) even more dangerous than the numbers say; or b) much less dangerous than the numbers say. Even if b) is true, however, it is still plainly dangerous — especially when it’s done without a helmet.
Kai Ryssdal: Time now for a little Freakonomics Radio. It's that moment every couple of weeks where we talk to Stephen Dubner, the co-author of the books and blog of the same name. It is the hidden side of everything. Dubner, it is so good go talk to you again, man.
Stephen Dubner: And to you, Kai. I missed you, too. How's your summer been?
Ryssdal: Good, good. Busy, busy, but good.
Dubner: 'Tis, of course, the season for outdoor activity -- some of which I'm here to tell you can have a very significant downside.
Ryssdal: Like what? Sunburn and mosquitoes bites? What?
Dubner: No, I'm actually talking about death. I hate to be a killjoy in the middle of summer, but I thought it might be worthwhile to look at the relative danger of some of America's favorite summertime activities.
Ryssdal: All right.
Dubner: So let's start with motorcycling. Here's Randa Samaha from the National Crash Analysis Center.
Randa Samaha: Motorcyclists are very vulnerable road users. For every 100 million vehicle mile traveled, there are over 24 riders killed.
Ryssdal: So when I was 20-something years old, I told my grandfather that I wanted to buy a motorcycle and he said I would sooner kill you with my bare hands. He was a doctor.
Dubner: Good advice. I don't know if you own a boat, Kai, but the boating statistics are a little bit frightening. Here's Mike Baron with the U.S. Coast Guard.
Mike Baron: We're roughly down to about, say, 6.2 deaths per every 100,000 boats.
And swimming, something most of us do -- I do a lot of in the summer. Here's Julie Gilchrist with the Centers for Disease Control and Prevention.
Julie Gilchrist: Overall the drowning rate in the United States for all ages is 1.29 per 100,000.
I couldn't find any stats on golfing because that's how I spend my free time. I think that's relatively safe. But skydiving, here's Nancy Koreen from the U.S. Parachute Association.
Nancy Koreen: There's been an average of maybe 22 fatalities a year, which is about seven per 1 million skydives.
Ryssdal: OK wait. Seven per million versus all those others, which is not so bad.
Dubner: Yeah, not so many. The motorcycle death rate is based on the number of miles traveled. Swimming deaths, meanwhile, are counted on a per capita basis. Skydiving deaths, based on the number of jumps. And of course, a lot fewer people go skydiving every year than go swimming.
Ryssdal: Help me out here, though, oh Freakonomics-Obi-Wan. What is the message here? Are we... Oh, I know what it is. We're scared of the wrong thing.
Dubner: That is exactly right. Human beings are generally quite bad at assessing risk. We tend to get worried about the big, anomalous events. Shark attacks, for instance, which on average kill fewer...
Ryssdal: You know why? Cause they're scary!
Dubner: They are scary and they get a lot of news coverage and then when they get a lot of news coverage we're convinced that they are a lot more common than they are. Five people on average worldwide die from unprovoked shark attacks. Meanwhile, in the U.S. alone in a given year, 4,500 people die from motorcycle accidents and another 4,000 or so from drowning.
Ryssdal: Yeah, but here's the thing: I could step off the curb in front of Marketplace global headquarters here this afternoon on my way to get a cup of coffee...
Dubner: God forbid, but yes you could.
Ryssdal: And I could get hit by a bus. What am I supposed to do?
Dubner: You're going to do what you want to do.
Ryssdal: Yes I am.
Dubner: I'm not saying you should be overly scared of things you shouldn't be, but there is a lot to learn looking at these numbers, just taking a step back and doing it. One piece of data that really jumps out at you is this -- the ability of alcohol to make bad things happen. So listen to this: About 30 percent of all motorcyclists who died were legally drunk. The Coast Guard tells us that alcohol was the primary contributing factor in about 16 percent of the boating fatalities.
Ryssdal: What about skydiving? People don't drink and skydive, do they?
Dubner: There are no hard and fast stats on it. We did ask. Here's Nancy Koreen again at the U.S. Parachute Association.
Koreen: For the most part, skydivers aren't really interested in doing that kind of thing. Skydiving is fun enough. You're having a good time and why would you add that extra element of risk?
Dubner: You know, Kai, this raises an interesting point. If an activity is prima facie dangerous, maybe it scares people from away from adding a layer of danger by drinking or something like drinking.
Ryssdal: Yeah, but hang on a minute because motorcycling is prima facie dangerous. But people drink and motorcycle all the time.
Dubner: To some people it is, to some people plainly it's not. I tend to agree with you, especially riding a bike without a helmet. Helmets are estimated to prevent about 40 percent of crash deaths among motorcyclists and yet there are a lot of motorcyclists out there who would much prefer to ride a bike than to not and to ride a bike without a helmet. Look, if safety is your primary concern this summer -- I'm not saying it should be -- but if it is, I've got the ultimate activity for you and everybody out there. You stay inside, you listen to your radio.
Ryssdal: Stephen Dubner.
Dubner: Taking the coward's way out.
Ryssdal: Ay man, I'm all right with that. Freakonomics.com is the website. He's back in a couple of weeks if he stays safe out there.
Dubner: Kai, tsk tsk tsk.
Ryssdal: You've got to be safe.