Seatbelts not only save lives --- they prevent tragedies

photo credit: AlamosaCountyPublicHealth via photopin cc

Everyone in the New York area has by now heard the tragic story of a young pregnant couple killed on their way to the hospital when their car was hit from the side by a hit-and-run driver (now identified as someone with an arrest record including recently driving under the influence of alcohol, but it's still unknown who was at fault.) The baby was delivered but sadly died because he was only 6 months gestation.  As tragic as this story is, the real tragedy is that the woman and possibly her husband and child might be alive today if they had been wearing seatbelts.

The couple was being driven in a 2008 Toyota Camry, a very safe car, but the woman was thrown from the car, meaning that she could not have been wearing a seatbelt.  The IIHS ratings for this car for a side impact give this car this highest rating for both passengers and drivers, and the driver walked away relatively unharmed.  Seatbelts reduce by half the risk of mortality from motor vehicle accidents, and certainly prevent passengers from being thrown from vehicles.

This couple was not alone in not wearing seatbelts in the backseat of a taxi, which is all-too-common behavior, although illegal in New York State.  Police are even allowed to stop cars for seatbelt non-use, but only drivers and front seat passengers can be ticketed.

A paper published last year in the journal Injury Prevention notes that the press often labels events as "freak accidents."  People mourn accidents, but journalists afraid of being seen as blaming the victims fail to communicate that many accidents could be prevented.   

Few accidents are truly freak accidents.  Many injuries, deaths, and tragedies can be prevented through sensible precautions, including wearing seatbelts.  There is no excuse not to wear a seatbelt, ever, even riding in a taxi.  New York State should expand its seatbelt laws to allow ticketing passengers.  If all passengers consistently wore seatbelts, we would have many fewer such tragedies. 

New study on the determination of different suicide attempters

People with guns in the house are more likely to commit homicide or suicide, according to hundreds of studies in the injury prevention literature. This difference exists even for households that have owned a gun for years, which means that in most cases, the gun was not bought for the purpose of a homicide or suicide that happened years after purchase. The common interpretation of the data is that many people have impulses that might lead them to homicide or suicide, but those who have a gun available can carry out their impulse quickly and easily, so are more likely to do so. By contrast, the suicidal/homicidal impulse does not last long enough for people to actually go and specially buy a gun for the purposes of carrying out their impulse.

Now a study finds that people who attempt suicide by gun are only moderately more likely to attempt again and successfully kill themselves. It may be the case that in many of the gun attempted suicides, the suicidal attempt was just the fulfillment of an impulse facilitated by gun access. If a gun were not available, certainly some people could be determined enough to actually go out and apply for a gun permit and then get a gun, but for many people the impulse would dissipate, and they would not have carried out the impulse.

Other suicide attempt methods associated with only moderate likelihood of a later successful suicide are gassing, jumping from a height, or drowning, and those with low likelihood of successful suicide are cutting and poisoning. Those with high likelihood of successful suicide are hanging, strangulation, or suffocation.

Likely gender is also involved. Cutting and poisoning are more common among women, and women are less likely to be successful at suicide.

The hypothesis about impulse being the cause of gun attempted suicides implies that most of the methods with low or moderate chance of successful later suicide are easily accessible and implemented, and indeed many involve materials easily available and could conceivably be carried out impulsively. The methods with high likelihood of later suicide also involve easily accessible materials, but may involve psychic costs that make them difficult to implement.

In short, I think the Supreme Court may have just increased the suicide and homicide rates by allowing more people easier access to guns that can be available quickly and easily enough to fulfill an impulse that would otherwise dissipate.

Positive predictive values and gun control

The US has a number of workplace and school shootings, and each incident goes the same way. Media dig up events from the perpetrator's past (putting the perpetrator's name everywhere when the perpetrator's name really should forgotten, and the victims the ones who are remembered), including criminal record, complaints from co-workers, qualitative assessments of the shooter's mental health, and random anecdotes, and all of these events are assembled to answer the question of whether someone could have known that the perpetrator was so crazy.

While some of these incidents from a perpetrator's past are indeed crazy, they have poor positive predictive value: the most recent shooter apparently punched a woman over a booster seat at an IHOP. But such ironic and strange incidents happen all the time, which I know as an avid reader of News of the Weird. Attempting to predict who will go bezerk is like looking for a needle in a haystack: many people do minor strange, crazy things, and even do so multiple times, but most people who do minor strange things will not commit homicide. Even looking at more severe incidents, such as shooting a brother at age 20, may not necessarily predict future violence. Though allegedly sending a bomb to a dissertation committee member seems more likely to predict future violence, she was cleared of that charge.

Attempting to predict who will snap begs the question. We can't. Even if we had Big Brother comprehensive databases of every person's past, and were willing to disregard rules of evidence and dropped charges, we couldn't predict severe violence. The real issue is not which people are likely to snap, but rather why our gun control policy allows people such easy access to firearms that when they do snap they can do so much damage. Human psychology is fallible, but in countries without easy access to firearms, the damage comes in the form of broken objects, bruises and broken bones, and perhaps even a stabbing. Firearms create more damage, and damage that is most likely to be deadly.

. . .

Speaking of News of the Weird, here's one from last year about a Yale PhD and professor:

Love Can Mess You Up: Before Arthur David Horn met his future bride Lynette (a "metaphysical healer") in 1988, he was a tenured professor at Colorado State, with a Ph.D. in anthropology from Yale, teaching a mainstream course in human evolution. With Lynette's guidance (after a revelatory week with her in California's Trinity Mountains, searching for Bigfoot), Horn evolved, himself, resigning from Colorado State and seeking to remedy his inadequate Ivy League education. At a conference in Denver in September, Horn said he now realizes that humans come from an alien race of shape-shifting reptilians that continue to control civilization through the secretive leaders known as the Illuminati. Other panelists in Denver included enthusiasts describing their own experiences with various alien races. [Rocky Mountain Collegian, 9-28-09]

Bumper sticker of the day

"DON'T DRINK AND PARK: Accidents cause people"

I saw this bumpersticker last night while driving home from a Harvard interviewing workshop. It was just text. Now that I google the phrase, I find some depictions that definitely aren't the classical meaning of "parking."

Traffic safety: speeding

Traffic safety is a big problem for adolescents. Injury is the leading cause of adolescent death, and traffic accidents where an adolescent is the driver is probably a large portion of that. Most studies of the question that I've heard of have concluded that everyone would be much better off if driving licenses weren't given until 18, and some places have instituted graduated licenses for 16 and 17 year olds.

With that background, here is a study of adults about the perceptions of whether speeding is safe: the vast majority of adults perceive speeding is safe, and safety is proportion to their perception of their likelihood get caught. I've observed this myself: everyone knows the slogan "speed kills", many know that kinetic energy is proportional to the square of velocity (i.e., so each incremental speed increase raises the risk even more). Some may even know that the majority of children survive being hit by a car going 25 mph, but the majority die being hit by a car going 40 mph. And everyone speeds. It may be an issue of overconfidence in driving abilities since nearly all drivers believe they are above average drivers; availability, since all drivers have either gotten a ticket or know someone who has, but few know those who have been in accidents; and all kinds of other psychological fallacies.

With this attitude prevalent among adults, it is almost unimaginable that adolescents would get a safe message about driving. It may even be futile to try to change adolescents' attitudes and behavior in the face of such widespread adult opposition. It seems that any campaign to prevent adolescent traffic injury would have to start with adults' attitudes, but how? How much increased enforcement of speed limits would it take? Is that even possible in crowded urban highways where the average speed is 10+ mph faster than the posted speed limit?

Here's the paper's abstract:

In recent decades, it has become more common for speed limits to be set for political reasons rather than for safety reasons. As a consequence, the motoring public seems to have increasingly begun questioning the rationality of speed limits. This is evident in observed speed data that show that the majority of drivers routinely exceed posted speed limits. A key motivating factor in drivers’ tendency to exceed the speed limit is that they believe that the excess speed does not threaten safety. This paper, specifically studies this matter by using a survey that asked drivers how fast above the speed limit they feel they can drive before safety is threatened. A probabilistic model is estimated using data gathered from 988 drivers in Indiana. Estimation findings show that drivers’ perception of the speed above the speed limit at which they will receive a speeding ticket is a critical determinant of what they believe is a safe speed – suggesting that enforcement plays an important role in safety perceptions. Other variables found to be significant factors in determining the speed above the speed limit at which safety is first threatened include age, gender, being previously stopped for speeding, and drivers’ ethnicity.