Charles Wheelan, Ph.D. The Naked Economist

I've just come back from New Orleans, where by a strange confluence of scheduling the BCS national championship football game overlapped with the annual meeting of the American Economic Association (AEA).

Bourbon Street was awash with thousands of Ohio State fans (red), thousands of LSU fans (purple), and thousands of economists (pasty people in suits). There's nothing quite like watching a Nobel Prize winner do a Jell-O shot off the stomach of an Ohio State cheerleader. (OK, I didn't actually see that, but it was theoretically possible.)

Big, Not So Easy

The BCS national championship is now old news, so I'll confine myself to the economists. One purpose of the annual meeting is to present a thousand or so papers on topics ranging from food stamps to prostitution. The most interesting session I sat through was not about saving Africa or fixing the public schools; those kinds of bold topics are often disappointing, because it turns out that we don't really know as much as we'd like.

Instead, a session with four papers on a more mundane topic caught my eye: traffic safety. Each study does what I think economics does best: 1) Ask a socially relevant question, and 2) Use data to answer that question, hopefully in a way that informs and improves public policy.

One of the papers was by Steven Levitt (the Freakonomics guy), and he's always good at stirring things up a bit. In fact, he said this paper has generated more anger than any work he's ever done, including his study that links legalized abortion to lower crime a generation later.

Counterintuitive Conclusions

I'll start with the socially relevant questions:

1. Do car seats for children over age two actually make them safer, compared to just wearing a regular seatbelt?

2. Do graduated licenses for young drivers make the roads safer? (Graduated licenses place limitations on new drivers during a specified learning period. Depending on the state, for example, they may only be allowed to drive during the day or with an adult in the car.)

3. Do motorcycle helmets save lives?

4. How dangerous are senior drivers?

The answers are:

1. Probably not.

2. Yes, but not for the reason you think.

3. Yes, definitely.

4. Very dangerous, but mostly to themselves.

The interesting part is how researchers come to these conclusions. I'll start with the finding that car seats for kids over age 2 probably aren't any safer than just putting them in the back seat with a regular seatbelt.

Sit Tight

Steven Levitt, along with coauthor Joseph Doyle from MIT, have analyzed large amounts of traffic accident data, some of it linked to hospital admission data, and find no significant difference in deaths or serious injuries between children restrained in a car seat and children restrained by a regular lap and shoulder seatbelt. There do appear to slightly more minor injuries (e.g., complaints of pain) to children in seatbelts relative to car seats. Levitt suggests that the cost of those minor injuries does not justify all the money we spend on car seats.

This seems heretical, given all the information we've been bombarded with about the importance of car seats. However, all of the data demonstrating their effectiveness simply compares car seats to no restraint at all. There's never been a comparison with seatbelts, which also seem to work well. In fact, Levitt and Doyle went to a crash test laboratory and ran their own crash tests with child dummies. They found that the effectiveness of the lap and shoulder seatbelt would've passed all federal requirements for car seats.

Car seats certainly don't make anything worse. One inadvertent advantage is that they make it far more likely that parents will put kids in the back seat instead of the front, which matters a lot for safety. Other countries, such as Canada, have regulations on car seats that are stricter than any U.S. state; perhaps those car seats bestow greater safety advantages. For now, however, Levitt (who has children) says that the most important reason to put young kids in car seats is that they sleep better.

Graduating Behind the Wheel

What about letting young drivers learn gradually? According to researchers from the RAND Corporation (a think tank), graduated licenses do make the roads safer, but not necessarily by making teens better drivers. Instead, graduated licenses just keep them off the road more, particularly with restrictions on night driving. Graduated licenses keep young drivers out of the car for long stretches relative to states that have fewer restrictions for the same age group. Teens who aren't in cars can't crash.

The authors find no evidence that graduated licenses produce better drivers. This raises interesting questions: Will the young drivers using graduated licenses simply have more accidents when they get older and spend more time on the road? Or will they be more mature then and make better, less risky decisions?

I suspect it's the latter; teenagers do particularly idiotic things. I vividly recall how much fun it was when I was 16 to drive around with Alex Irvine on the roof of my car. If research confirms my supposition, then the best policy might simply be to raise the driving age. This isn't just an academic question -- roughly 1,000 teenagers die every year in vehicle accidents.

Born to Be Wild?

Between 1997 and 2005, the number of motorcycle deaths roughly doubled, mostly because there are a lot more motorcycles on the road. Some 4,000 motorcyclists die a year -- roughly 10 percent of all traffic fatalities. Do motorcycle helmets make a difference?

Yes. The authors conclude: 1) Helmets protect riders, saving lives, and 2) Helmet laws put more riders in helmets (and keep some riders off the road), also saving lives. But getting to that conclusion is trickier than it would appear.

The big problem is that a direct comparison of fatality rates between riders with helmets and riders without helmets won't tell you very much. They may be different kinds of riders. Motorcyclists may put on a helmet when they expect to be riding faster or in more dangerous conditions. Or perhaps the safest riders are the ones who choose to wear helmets -- in which case their lower fatality rates would be the result of their safe riding, not the helmet.

Some motorcycle enthusiasts have argued for a long time that helmets might actually make things worse by obstructing the rider's vision or causing neck injury in the case of a crash. So researchers use clever techniques to isolate the effect of the helmet alone. For example, one approach is to study accidents in which one rider on a motorcycle is wearing a helmet and the other is not. This research, and other complementary approaches, all find that motorcycle helmets protect riders.

The libertarian in me feels compelled to point out that motorcyclists are most likely to harm themselves. Therefore, the fact that helmets save lives doesn't necessarily justify laws requiring that motorcyclists wear them. One of the study's authors suggested (in true economist fashion) that motorcycle riders should be exempt from helmet laws as long as they agree to be organ donors.

The 90-Year-Old Behind the Wheel

Older drivers die in car crashes at rates that look nearly as alarming as teen drivers. And the further they get past age 65, the worse it looks. There have been some highly publicized cases of older drivers losing control of their vehicles and doing horrible harm. How worried should you be about that old guy in the Cadillac driving slowly with his turn signal on?

Not as worried as the statistics might suggest, according to a study by David Loughran and Seth Seabury, both from RAND. True, older drivers are "moderately more likely to cause a crash," but the fatality numbers are inflated by the fact that the elderly are far, far more likely to die if a crash occurs than are middle-age adults or teens. By and large, older drivers are doing most of the damage to themselves.

This has divergent implications. On the private level, families worried about their older drivers should be worried. A disproportionate number of older drivers die in car crashes. But from a public policy standpoint, older drivers present less of a risk to everyone else than the raw numbers would suggest. Unlike teenage drivers, the elderly are not radically more likely to kill the rest of us.

AEA vs. BCS

This stuff matters. The Centers for Disease Control declared falling auto fatalities as one of the 10 great public health achievements of the 20th century. Those gains were built upon research like what I've just described.

I suspect the OSU and LSU fans had more fun in New Orleans than the economists. I'm hoping the economists' contributions will be more enduring.