Thank you Darren. Just to clarify, from what I recall the "Freaks" didn't tell people to ditch boosters, I believe their issue was with complex harnesses.
A matter of semantics, I guess. No, they didn't say to ditch their boosters. At the very least, they admit that carseats and boosters are no worse than seatbelts for kids 2 and over. On the other hand, the conclusion of their NYT article was that a DVD player may be just as effective as a car seat or booster, for about the same price. How do studies and statements like this get interpreted by the masses? You might as well tell them to ditch their boosters, but it's not as easy to CYA that way, of course.
From an engineering standpoint, it does seem a bit silly to strap someone to something, and then strap that something to a seat.
From a "Keep it Simple" perspective, it does seem silly. One more component with a possibility to fail or be misused. The issue is one of ejection and energy absorption, though. You want more points of restraint to couple the passenger to the vehicle to maximize the ride down time afforded by the crushing frame of the vehicle.
Seatbelts are compromised because they are designed for adults and for comfort. Fewer points of restraint that do not fit to the strongest points of a child's body do not make for a great restraint system. Ideally, there would be an easy to use, built-in restraint in new vehicles, but people don't buy them so manufacturers dont make them. So, we are stuck with an adapter of sorts.
I agree that a truly useful study needs to look at injuries, and I believe that is a flaw of their initial study, they only looked at deaths. I haven't read the new book so I don't know if they looked at injuries since.
And there is the issue as to what you omit from your data. Each study includes or omits various data for one reason or another.
As you probably know, they were able to do a single test of a car seat vs. seat belt and using that test the results were comparable.
As I said- if you do this test, the important factors are the fit to the child and the abdominal injury measurements from a lap belt. Did their tests consider typical fit of seatbelts, )(or only) ideal fit? Did they have abdominal injury sensors of some type? I suspect not.
What really worries me is it was very difficult for them to commission that test and no testing company would agree to do that test for them, unless they kept the name of the company a secret, in order not to upset the car seat manufacturers. If these companies trust their product so much there shouldn't be an issue with testing against the lowest common-denominator.
Assuming the test is done with proper controls and done without bias. If I was an engineer at a testing lab and thought a test was being done improperly or with questionable intention, I might have second thoughts, too. After all, a laboratory's reputation would be at stake.
I'm also curious where all this seat-belt vs car seat data comes from. As far as I know car seats are mandatory for small kids across North America. Who are these people who are putting their kids in seat belts? Are all these people breaking the law? Do these stats come from jurisdictions where seat belts are allowed for kids 2 years and older (with a booster of course)?
As with any law, many people ignore it, if they know about it at all. Some come from cultures where it simply isn't even considered. Kids ride on an adult's lap. There is also poverty. Many families simply don't buy one or they use those that are obsolte or broken. Heck, many adults still don't wear seatbelts, despite primary moving violations that have been in effect for years.
I would really like to see data that compares the two devices fairly. What I REALLY don't want to see is policy mandating the use of expensive devices that is based on emotion, especially saying stuff like "how much is the life of your kids worth to you".
Motor vehicle crashes remain the #1 cause of death. Finding what works well to reduce these risks at minimal cost is apparently not an easy task. Many laws like this are backed by statistics when written and when discussed in legislatures. Others are started by grass roots campaigns with one parent or family who lost a child. They can be repealed the same way. The Freakonomics authors could make a nice lobby of their own to do this. I wonder if they have?
I agree completely. Since I started looking at this I find that there's a compelling case to rethink this whole "must use a 5-point-harness" thing. As a parent, I would like to know that I'm not being suckered into buying a device that doesn't really do what I'm told it does. I'd rather spend the money on something I KNOW will improve the safety, and I'd like to be able to know how much safety my money is really buying. And as a concerned citizen I'd really like to know that millions of dollars are being spent in the right place. For example, if instead of mandating more complex harnesses we could mandate seat belts that actually fit kids, or more rear air bags etc. and that would save more lives, wouldn't that make sense? It would be so much more convenient if my car came with a seat that can safely strap both a child and an adult without having to install an inconvenient device. I understand that some cars already do have that.
I have a squirmy 4-year old. By the time he's done moving around for 5 minutes antagonizing (or being antagonized by) his siblings, his lap and shoulder belts are loose and the shoulder belt is hanging off his arm. You know, it's definitely possible to fit a 3-year dummy in a seatbelt, keeping it tight and having it minimize head excursion and head/torso injury measures for a crash test on a test bench. What about with a real kid in a real car, where seatbelts vary a lot? If you have a young child that sits as still as a dummy from the time you belt it to the time it crashes, that's great. Watching my son, I see him being ejected or having that loose lap belt going into his abdomen, where crash dummies have no measure of injury criteria. Now if I put him into a 5-point harness, he stays restrained at more points and cant wiggle them loose. That is why you need to address the typical fit of a belt in a seatbelt vs. a booster, and not all boosters are created equal, either.
Again, in an ideal situation, a seatbelt can theoretically provide as much frontal crash protection as a booster or 5-point harness. The difference appears to be the potential for misuse of a booster or harness, vs. the potential for poor fit or a squirmy kid that might make a seatbelt unsafe. The advantage I have is that I can make sure a 5-point harness is installed correctly and is used correctly. I can also make sure a booster is fit correctly initially, too. That moves me well out of the data set used by Freakonomics, as would be true for any parent with a modest education on the topic or concern about the risks of misuse. With a seatbelt, the belts may not fit well at all to start, and with seatbelt or booster, the child has more ability to negate their efficacy while my attention is on the road.
As with all such studies that seem to contradict each other, there are two sides to the story. You won't hear them both from the Freakonomics authors. Going with the status quo doesn't sell books. You won't hear them both from the government or insurance/medical research teams either. That's not what their grants or funding pay them to do, after all. It's too bad both sides won't get together to sort it all out. You'd think that all these PhD's who should have a grasp of scientific method could figure out the real story.