In this video, Steve Levitt and Stephen Dubner talk about their finding that you are 8 times more likely to die walking drunk than driving drunk.
Levitt says this
“anybody could have done it, it took us about 5 minutes on the internet trying to figure out what some of the statistics were… and yet no one has every talked or thought about it and I think that’s the power of ideas… ways of thinking about the world differently that we are trying to cultivate with our approach to economics.”
Dubner cites the various ways a person could die walking drunk
- step off the curb into traffic.
- mad dash across the highway.
- lie down and take a nap in the road.
Which leads him to see how obvious it is ex post that drunk walking is so much more dangerous than drunk driving.
I thought a little about this and it struck me that riding a bike while drunk should be even more dangerous than walking drunk. I could
- roll or ride off a curb into traffic.
- try to make a mad dash across an intersection.
- get off my bike so that i can lie down in the road to take a nap.
plus so many other dangerous things that i can do on my bike but could not do on foot. And what the hell, I have 5 minutes of time and the internet so I thought I would do a little homegrown freakonomics to test this out. Here is an excerpt from their book explaining how they calculated the risk of death by drunk walking.
Let’s look at some numbers, Each year, more than 1,000 drunk pedestrians die in traffic accidents. They step off sidewalks into city streets; they lie down to rest on country roads; they make mad dashes across busy highways. Compared with the total number of people killed in alcohol-related traffic accidents each year–about 13,000–the number of drunk pedestrians is relatively small. But when you’re choosing whether to walk or drive, the overall number isn’t what counts. Here’s the relevant question: on a per-mile basis, is it more dangerous to drive drunk or walk drunk?
The average American walks about a half-mile per day outside the home or workplace. There are some 237 million Americans sixteen and older; all told, that’s 43 billion miles walked each year by people of driving age. If we assume that 1 of every 140 of those miles are walked drunk–the same proportion of miles that are driven drunk–then 307 million miles are walked drunk each year.
Doing the math, you find that on a per-mile basis, a drunk walker is eight times more likely to get killed than a drunk driver.
I found the relevant statistics for cycling here, on the internet. I calculate as follows. Estimates range between 6 and 21 billion miles traveled by bike in a year. Lets call it 13 billion. If we assume that 1 out of every 140 of these miles are cycled drunk, then that gives about 92 million drunk-cycling miles. There are about 688 cycling related deaths per year (average for the years 200-2004.) Nearly 1/5 of these involve a drunk cyclist (this is for the year 1996, the only year the data mentions.) So that’s about 137 dead drunk cyclists per year.
When you do the math you find that there are about 1.5 deaths per every million miles cycled drunk. By contrast, Levitt and Dubner calculate about 3.3 deaths per every million miles walked drunk.
Is walking drunk more dangerous than biking drunk?
Here is another piece of data. Overall (drunk or not) the fatality rate (on a per-mile basis) is estimated to be between 3.4 and 11 times higher for cyclists than motorists. From Levitt and Dubner’s conclusion that drunk walking is 8 times more dangerous than drunk driving we can infer that there are about .4 deaths per million miles driven drunk. That means that the fatality rate for drunk cyclists is only about 3.8 times higher than for drunk motorists.
That is, the relative riskiness of biking versus driving is unaffected (or possibly attenuated) by being drunk. But while walking is much safer than driving overall, according to Levitt and Dubner’s method, being drunk reverses that and makes walking much more dangerous than both biking and driving.
There are a few other ways to interpret these data which do not require you to believe the implication in the previous paragraph.
- There was no good reason to extrapolate the drunk rate of 1 out of every 140 miles traveled from driving (where its documented) to walking and biking (where we are just making things up.)
- Someone who is drunk and chooses to walk is systematically different than someone who is drunk and chooses to drive. They are probably not going to and from the same places. They probably have different incomes and different occupations. Their level of intoxication is probably not the same. This means in particular that the fatality rate of drunk walkers is not the rate that would be faced by you and me if we were drunk and decided to walk instead of drive. To put it yet another way, it is not drunk walking that is dangerous. What is dangerous is having the characteristics that lead you to choose to walk drunk.
These ideas, especially the one behind #2 were the hallmark of Levitt’s academic work and even the work documented in Freakonomics. His reputation was built on carefully applying ideas like these to uncover exciting and surprising truths in data. But he didn’t apply these ideas to his study of drunk walking. Of course, my analysis is no better. I just copied some numbers off a page I found on the internet and applied the Levitt Dubner calculation. It only took me 5 minutes. (And I would appreciate if someone can check my math.) But then again, I am not trying to support a highly dubious and dangerous claim:
So as you leave your friend’s party, the decision should be clear: driving is safer than walking. (It would be even safer, obviously , to drink less, or to call a cab.) The next time you put away four glasses of wine at a party, maybe you’ll think through your decision a bit differently. Or, if you’re too far gone, maybe your friend will help sort things out. Because friends don’t let friends walk drunk.
30 comments
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December 16, 2009 at 7:57 am
jeff
Note: nasty comments are being deleted.
December 16, 2009 at 8:27 am
Noah Yetter
I agree. I found his argument for doing the calculation by mileage to be highly specious, because distance is a huge factor in the walk/drive calculation. Walking from my favorite bar to the place I lived during college is only 2.2 miles by Google Maps walking mode, not really a big deal (though I often took the bus). Compare that to where I currently live, 10.1 miles away, which I’m not walking under any circumstances, not because it’s dangerous but because I’m lazy and it would take 4-5 hours.
Bottom line is his conclusions are based on make believe and excessive extrapolation, and should not be used for anything except a lesson in “how not to use statistics.”
December 16, 2009 at 8:58 am
Jack
One thing not discussed is the consequences of driving drunk, sure the car protects you from being harmed even if you make a mistake and crash, but how will that mistake affect others (read pedestrians)? Just saying that its safer to drive home drunk rather than walk is a scary way to forget how many innocent people that have been affected by such a truly bad judgement.
December 16, 2009 at 10:43 am
zbicyclist
Other interesting sidelights:
1. I wonder how many of the drunk pedestrians might be killed while they are walking to their parked cars in order to drive home? Those first 100 feet might be the deadliest.
2. Does anybody really care if drunk drivers kill themselves? I don’t much care. But I’ve had 3 friends/relatives killed by somebody else driving drunk, and I care about that. Do drunk walkers kill others?
3. Similarly, if we had real statistics on drunk bicyclists (and you don’t claim to) we might find that drunk cyclists are cycling because they can’t drive due to a previous DUI — hardly a random sample of anything.
December 16, 2009 at 1:01 pm
stephen
I cycle everywhere – out of choice, not DUI – and my drunk miles probably equal, if not outweigh, sober ones. I have never been in an accident on my bike, sober or drunk. Any self-respecting cyclist would never “roll or ride off a curb into traffic,” because they would never ride on the fucking sidewalk. That’s the surest way to die, no matter what your mental state.
Bottom line, a cyclist either knows what they’re doing or they don’t. If you’re unsure, stick to the bike paths.
December 16, 2009 at 1:09 pm
jay
I agree with most of your points but would add that you may choose your mode of transport depending on just how drunk you happen to be at the time.
A. If you’re drunk driving, it’s possible you ‘feel’ you’re okay to drive regardless of the legal disincentives in doing so.
B. If you’re drunk biking, you need to be at least confident enough in your drunken ability to operate a bicycle safely to your home.
C. If these two above options are undesirable or unavailable, the third option you have available to you is drunk walking. It is the slowest of the options, and the one most people would believe themselves to be capable of, since nearly everybody walks and is fairly confident in their abilities.
And so the drunkest people may have self-selected themselves to go for a walk instead of a bike or drive.
I guess the main point of your post, though, is just that someone is claiming to know something that they probably don’t know and deep down might even know that they don’t know and this is something that you should generally avoid unless you’re every macroeconomist ever.
December 16, 2009 at 1:34 pm
jeff
🙂
or a parent.
December 16, 2009 at 2:22 pm
Alex
If you’re really at risk of lying down to take a nap in the middle of the road (which I wouldn’t call “walking home”), you should probably neither walk nor drive home.
December 16, 2009 at 2:50 pm
jeff
unless that’s your home.
December 16, 2009 at 5:10 pm
Mike
Levitt ties “If you assume…” followed by a very weak assumption and then comes up with this ^fact^, “on a per-mile basis, a drunk walker is eight times more likely to get killed than a drunk driver.”
For me the whole thing a numerical fairytale. I’d be interested to see what he could have done by spending say an hour collating the data that’s out there. Each road death, for pedestrians, cyclists, and motorists, will have had a coroner ascertain blood alcohol, that would be the starting point for modelling you’d think.
December 16, 2009 at 8:02 pm
Adam Bossy
A response to similar arguments made here: http://freakonomics.blogs.nytimes.com/2009/12/14/what-bothers-people-about-superfreakonomics/
December 16, 2009 at 8:13 pm
Dave Ak
The premise is fallacious. The real measure is how many deaths per minute of the activity. Also, if a drunk walker wanders out in front of a drunk driver, well, you figure it out.
December 16, 2009 at 9:36 pm
cak
I do a lot less crazy stuff when I ride drunk. For example, I will stop at yellow lights.
Still, these extrapolation is one of the worst I have ever seen Steven use.
December 16, 2009 at 10:34 pm
anon
If I can trackstand, I’m not drunk.
December 17, 2009 at 10:04 am
JO'N
In any case, when was the last time a drunk walker killed someone ELSE?
December 17, 2009 at 10:21 am
dailycrockett
I believe Levitt’s analysis also doesn’t take in account the most important factors people consider when deciding to walk or drive home drunk. Walking drunk could earn you a public intoxication charge, driving drunk can put you behind bars and that DUI can follow you forever. Furthermore when you walk/bike drunk, you are only putting yourself in danger. When you drive drunk you are putting everyone on the road in danger. When folks weigh the risks of walking/biking versus driving drunk, I think they are more concerned about meeting a police officer than their maker.
December 17, 2009 at 11:08 am
rana
But, you should also remember that Levitt & Dubner are not reliable on their “googling”. They have a way high number for miles driven after drinking–off by a factor of 10. Basic math 200 million drivers, 3 percent drive drunk each month (http://www.britannica.com/bps/additionalcontent/18/21515330/TwelveMonth-Prevalence-and-Changes-in-Driving-After-Drinking). Or about 6 million drivers and over the course of a year they have 130 million incidents of driving. Typical car trip is ten miles (4 trips per day 35 miles per day. 2001 nhts study) So that would be 1300 million miles. Total miles traveled was 2962,000 million miles. Drunk driving is 1 ile per 2251 miles traveled not 1 per 140. Deaths per million miles drunk is then about 9. How does that compare to being a drunk walker. Who knows? He makes it up. But among all walkers the death rate is 0.1 per million miles, compared to 0.01 for all drivers.
December 17, 2009 at 11:24 am
jeff
thanks!
December 17, 2009 at 2:06 pm
ottnott
A similar Quackonomics exercise would be to look at how many innocent bystanders are killed per mile by drunk walkers and drunk drivers, and conclude that we should allow vigilantes to wait in bar parking lots and “temporarily disable” any drunks attempting to drive.
December 17, 2009 at 2:16 pm
ottnott
My follow-up Quackonomics exercise is be to determine the trip-length threshold at which one should switch from driving drunk to walking drunk.
Using the Freak conclusion that drunk walking is 8 times more dangerous per mile, and assuming that the drunk walker is sober after 5 miles (about 2 hours) of walking, Quackonomics concludes that a drunk person should choose driving unless the trip is longer than 40 miles.
In seriousness, though, it would be interesting to find out how many of the drunk pedestrians were actually going anywhere. How many of them were homeless alcoholics just wandering around with a bottle?
The Freaks have jumped the shark.
December 17, 2009 at 7:45 pm
Alex
>>How many of them were homeless alcoholics just wandering around with a bottle?
Or sleeping in the middle of the road! Which — by the way — is *extremely* dangerous on a per-mile basis.
December 17, 2009 at 7:32 pm
links for 2009-12-17 « Blarney Fellow
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December 18, 2009 at 6:10 pm
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[…] Drunk Cycling In this video, Steve Levitt and Stephen Dubner talk about their finding that you are 8 times more likely to die walking […] […]
January 15, 2010 at 4:42 am
Dessius
this whole study proves that anyone can prove anything they want using available statistics. I listened to a top sales executive once say that he could prove both sides of an argument using the same statistics but just focusing or emphasising different parts. The best idea is not to do anything drunk other than sleep!
July 11, 2010 at 7:01 am
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[…] Drunk cycling […]
August 13, 2010 at 6:15 pm
Ausmess
Its always the automobile that kills the pedestrian or cyclist.
I’ve read enough selfish statements that focus on personal safety rather than the safety of others in my lifetime.
General rule is; personal safety comes at the expense of someone elses safety.
September 7, 2010 at 8:32 am
Riskbloggen » Rattfylla eller fyllepromenad?
[…] om man kör bil full, vad kommer man fram till då? Enligt författarna till Freakonomics är det åtta gånger högre risk att skadas att gå än att åka bil, förutsatt att man är onykter så […]
November 4, 2011 at 11:44 pm
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[…] P.S. THe Freakonomics blog deserves to be dinged another time, not just for claiming, based on implausible assumptions that “drunk walking is 8 times more likely to result in your death than drunk driving” […]
May 14, 2013 at 8:21 am
Al Camus
I realize my comment is well after the article date, but there is an important factor you did not consider and that is what is the typical “drunk bike”. In my view most drunk bikes are kid bikes or beat up mountain bikes which are not mechanically capable of generating much speed. Plus many of these bikes are likely stolen and lack maintenance .
So the typical drunk bike is undersized , poorly maintained, and has under inflated tires.
Accidents are mostly side tip overs and since the bike is undersized the falls are not as great and damaging to the person.
The best drunk bikes are made by Huffy and Magna.
December 3, 2021 at 2:08 am
karan
biology