Thursday, May 24, 2012

Cyclists with helmets ride faster

Part of the perennial discussion about cycling helmets is whether wearing a helmet results in cyclists riding faster on average, thereby taking more risks and increasing the likelihood of injury.  The idea originates in the concept of risk compensation whereby people adjust their behavior until some level of risk is reached.  The classic example taught in economics is the Peltzman effect regarding seat belt use.  The hypothesis is that when seat belts were commonly installed in automobiles and used, drivers took more risks on the road thereby offsetting the increased safety of using the seat belt.  In my own teaching experience, many students had a hard time accepting this.  So I suggested a counter example -- not my idea by the way -- whereby a big spike is installed in the middle of every steering wheel pointing at the driver.  Would drivers on average be more careful?  If you think yes, then if people are willing to risk compensate when danger increases, why would the reverse be false?

The Wall Street Journal summarized some recent research on the topic regarding bicycle helmets ...
From 2009 to 2010, free bicycle helmets were issued to 1,557 volunteers in Bordeaux, France. The subjects' average age was 32 years; 58% were women. Previous helmet users were excluded.
Data was collected daily at seven locations, each equipped with two cameras programmed to detect moving objects, isolate cyclists and calculate their speed. Cyclists were photographed from above and behind.
Helmet use was recorded in 99, or 3.8%, of 2,621 movements made by 587 cyclists captured on camera.
Cycling speed of helmeted men averaged 11.9 miles an hour compared with 10.4 miles an hour for unhelmeted men. Helmeted and unhelmeted women cycled at 10.2 and 9.9 miles an hour respectively, suggesting risk compensation is a male behavior, researchers said. That behavior disappeared when helmeted men cycled in areas where speeds were extremely fast and the objective risk of injury increased, the study found.
There are some important caveats about the unobserved cyclists and whether they are meaningfully different from those observed in the data.  Moreover, it can certainly be the case that volunteers are inherently different from the rest of the population.  Nonetheless, while this is a simple data point, it does support the notion that pushing for greater helmet use by cyclists is not necessarily welfare improving.

EDIT: The original article is gated and such that details of the experiment are fuzzy.  I can interpret the passage above a few ways that (subjectively) make the selection effects more or less relevant.

Thursday, May 17, 2012

I can run a country with my eyes shut?

Now that we're in the information age it's more than a bit ironic that the House voted to cut funding for the American Community Survey and the Economic Census in its latest appropriations bill.  As the old military phrase, "the fog of war" suggests, the military needs good information to be effective.  Not surprisingly it turns out that government, business, and society in general needs information to be effective.

From Businessweek ...
Tom Beers, executive director of the National Association of Business Economists, says that without good economic data, businesses would be “flying blind.” He adds: “You end up in a guessing game about what’s going on in the economy. The types of losses that result are far worse than what you end up spending to fund these surveys.”
More strikingly, from the same article ...
Contacted last week, economists at conservative think tanks Cato Institute, American Enterprise Institute, and the Heritage Foundation all expressed support for the data-gathering agencies since all three rely heavily on the statistics they produce to study the economy. “Those agencies are essential,” says Phillip Swagel, an economist and nonresident scholar at AEI. “The data they provide really tell us what’s going on in the economy. This shouldn’t be a political issue.”
Some people have suggested that state or local government agencies or private organizations might be able to fulfill the data gathering and processing responsibilities of the ACS and Economic Census.  The resources needed to design, organize, and execute effective surveys is nontrivial.  The science of survey design -- large surveys often have complex designs to realize large savings for a given precision -- as well as developing/maintaining an organization to implement it strongly suggests that there would be large economics of scale/scope with centralizing its function.  Moreover the alternative overlooks that data fits aspects of a public good quite nicely: (1) while you can impede people's access with some effort, it would be hard to exclude people from its results and costly to prevent people from sharing it and (2) one person's use of data does not impede another person's use of data.  So in a classical economic sense, it is something that government should do.

Theodor Geisel, Dr. Suess, once wrote I Can Read with My Eyes Shut! to encourage children to read.  But even my little boy knows that this is just a jest not to be taken seriously.  Let's not run a country with our "eyes" shut.

Thursday, May 10, 2012

Great advice

A hero of United Flight 232, Denny Fitch, died recently.  As an off-duty airline pilot, Fitch helped "land" Flight 232 after a turbine fan shattered severing the hydraulic lines needed to control the airplane by manually adjusting the throttles while sitting on his knees.  While Fitch was devastated by the 111 people that died, he eventually recovered from his injuries, returned to work as a pilot and eventually became a motivational speaker.  

From an interview in a documentary about the crash ... 

"What makes you so sure you're going to make it home tonight?" he said. "I was 46 years old the day I walked into that cockpit. I had the world ahead of me. I was a captain on a major U.S. airline. I had a beautiful healthy family, loving wife, great future. And at 4 o'clock I'm trying to stay alive."
From the Associated Press article
Fitch became a motivational speaker, who advised others that they should let their family and friends know how much they're loved.
Great advice by any standard.

P.S. The linked documentary above is great.  Highly recommended.