posted
This article is about a study that says that car seats reduce deaths by 21%. I was interested to see if you'd heard of the study and what you think of their methodology, since there's always one person every time this comes up who says, "But show me a study that proves I need a car seat..."
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posted
From the abstract of the journal article, here are the significant results:
quote:Compared with seat belts, child restraints, when not seriously misused (eg, unattached restraint, child restraint system harness not used, 2 children restrained with 1 seat belt) were associated with a 28% reduction in risk for death (relative risk, 0.72; 95% confidence interval, 0.54-0.97) in children aged 2 through 6 years after adjusting for seating position, vehicle type, model year, driver and passenger ages, and driver survival status. When including cases of serious misuse, the effectiveness estimate was slightly lower (21%) (relative risk, 0.79; 95% confidence interval, 0.59-1.05).
posted
There's a law in Ontario that requires all children under a certain hieght/weight to sit in a car seat. The age goes up to about 7-8 year olds.
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posted
CA, too-- 8 years or 80 lbs. (although after about 3 they go in boosters, not full car seats.)
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posted
Does anyone know if there are stats on the efficacy of the booster seats for older kids? I honestly think we're going too far with the 8 years, 80 lb thing. My 8 year old doesn't need to be in a booster seat any longer, the seat belt doesn't fit much worse than it does on me and she's as tall as some adult women I know (admitedly they are short adult women, but still.) Yet, because it's the law she's forced to sit in one, and because of that I can only put two kids on a seat that should hold three - the booster seats take up so much room it's nearly impossible for someone to sit between them. That makes my eight passenger van pretty darn near a six passenger one.
I can certainly see the need for seats up to the age of five or so, but after that, I wonder are we really saving a bunch of kids or are we fattening up the pockets of the companies that make booster seats?
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quote:Originally posted by ketchupqueen: CA, too-- 8 years or 80 lbs. (although after about 3 they go in boosters, not full car seats.)
Is it whichever comes first? If you're in middle school but weigh 75 pounds, you wouldn't need a booster seat, right? (Because if you do, I think I needed a booster seat until the beginning of high school. I'm a tiny, tiny person.)
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posted
Yes, whichever comes first. Although if your kid is 8 and not 80 lbs. and her legs do not hang comfortably over the edge of the seat when her bottom is at the back of the seat-- I think 4'9" is the standard height-- it is still recommended she use a booster, just not required by law.
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posted
Belle, there are other belt-positioning alternatives, but I believe that the laws were made because there really is a need for kids' restraints to be adjusted until that point. Now, I'm not sure that boosters are the only effective way to do it at that age; perhaps the laws should be re-written to allow for an acceptable alternative, like belt-positioners.
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posted
I'm confused as to why age and weight are the key factors. I would think height was the only thing that needed to be considered.
From what I know the problem with seat belts with regard to children and short adults is that they sit too low in the belt. Instead of going across their shoulder, the belt tends to go across their neck. In an accident, the belt can cause neck injuries and possibly strangulation.
As mentioned by KetchupQueen, there are belt positioners. The ones I'm familiar with clip the shoulder strap to the waste belt moving the junction father to the side to move the shoulder belt across the young person's shoulder and away from their neck.
So, again, why are age and weight the critical criteria, when height, or lack there of, seems to be the main risk factor?
One additional factor is passenger side airbags. Again a young person or a short adult are in the wrong position, and when the Bag is deployed, it hits them square in the face, when a substantial portion of the impact is intended to be absorbed by the shoulders and chest.
Most newer cars either have a manual switch to disable the passener's side airbag, or a sensor that detects the weight of the person sitting in the seat, and disable the airbag for a light weight person. Though, as I noted before, weight is not the critical factor; it's height.
posted
Age is also a factor, I believe; for instance, children should be rear-facing until 1 year old no matter how big they are. But as you get older, I think it gets more contingent on height and weight; I think that lawmakers just decided to stick with the "tried and true" requirements, changing it from 4 years and 40 lbs. to 6 or 60 and then 8 or 80. You know, politicians. I'm not sure that studies of belt-positioners other than belt-positioning boosters (the only recommended booster seats) have been done. That might be a factor in the laws.
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posted
A bill in Indiana that didn't pass was going to say 80 pounds and 4'9 but no age. I had a middle school teacher who was not quite that, she was thrilled.
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This study includes statistics from (again, quoting from the abstract):
quote:rear-facing and forward-facing car seats, and shield and belt-positioning booster seats
. Also, it was limited to children from 2-6 years of age (which seems odd with the rear-facing stipulation; I can't imagine a 2 year old in a rear-facing seat).
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posted
It is now recommended to keep children rear-facing as long as their carseats will allow (although not required.) If you had a very small 2-year-old and a very large carseat, I could see it happening. Emma didn't hit 20 lbs., the requirement for front-facing, until she was 14 months; her carseat was approved for rear-facing up to 30 lbs., which she still has not hit (although I think she's outgrown the approved height for rear-facing.) We did turn her front-facing, though, because she was starting to scream every time we put her in and we had space requirements.
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posted
Unfortunately the full text of the article isn't available online, so I couldn't check the methodology. However, I will say that the lead author (Elliot) has an impressive set of credentials and he's working in a pretty good program.
There are issues with relative risk analysis with children related to the need to counterbalance seating position with force vectors in the crash, and match on vehicle types as well. It usually makes for very small N in the data tables when all is said and done.
There are ways to boost the N and those give me some pause as well. For example, the NASS dataset referred to is a sample-based dataset and when dealing with the lowest frequency events one often has to contend with LOTS of variability in the data. I have caught several researchers violating rules and forgetting to apply the standard error of the estimates to their weighted data from those studies.
I suspect, however, since Elliot is a qualified biostatistician, he knows how to do this right and didn't make the same mistake that some of his colleagues (in an affiliated program) have made.
The other thing that always gives me pause is claims for huge effect sizes in studies of risk. 28% is big. Really big. That's a bigger effect than was found in the original studies of seatbelt effectiveness.
And even factoring in improper usage they got 21% effectiveness. That, makes me question this even more.
It'd be interesting to see their methods section, and learn the details behind what they considered "improper" use. And, if they excluded ANY cases.
Anyway, it's not totally implausible to get 28% effectiveness, but I'll reserve judgement, and say I think the research is probably credible, but...
(note, at least it's not a study by those lame Freakonomics guys who didn't know the dataset and made a bunch of bone-headed errors.)
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posted
My point, guys, was that it was limited to kids aged 2-6. I have one kid older than that, which the state now says has to be in a booster seat. I don't agree. I want to see clear cut evidence that an eight year old is really safer in a booster seat.
Also, where do you buy belt positioners? I've not seen one in any store I frequent. They only thing for sale for kids Emily's size is booster seats.
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I used to get these things free at safety conferences. Unfortunately, NHTSA has not supported the idea of belt-positioners (instead going with booster seats). I'm honestly suprised they didn't go so far as to try to ban the positioners, but I'll be interested to see what product liability statement comes on the one you get, Belle.
Btw, the simplest belt positioner I ever saw was a loop of stretchy material about 2.5" wide. you looped it around the belt near where the shoulder and lap belt meet (near the buckle) and it velcro'd tight around them. That was enough to lower the shoulder belt angle.
Personally, I do not know why the booster seat would be preferable to a belt positioner. I haven't really looked at the data for this issue, so I just have no clue as to whether there's any evidence that positioners have a problem that is solved by the booster seats.
I do like the idea of getting the belt off of anyone's neck. I have a problem in the backseat of my vehicle, and I'm 6'0". That darn belt hits at too steep an angle.
posted
Hmmm. I might have to get a belt positioner to take around with me, I have that problem in a lot of cars.
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posted
It's probably not a bad idea. I have thought about it as a thing to carry with me on trips because I rent so many different cars and they are all different, many of them sub-optimal.
Especially back seat belts which often don't have any vertical adjusters on the shoulder belt.
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Here's another: [http://www.mileskimball.com/jump.jsp?itemType=PRODUCT&itemID=3474]Miles Kimball casa de cr@p[/url]
Not happy that it's a "miles kimball" product, but it is the kind of thing I was thinking of as a simple solution.
Here's apparently the same thing, with a picture. not sure if I like the plastic clip idea. The one I had was just stretchy fabric & velcro. If something happened to it, it wasn't going to send shards flying...
I'm leery of that "tested by a NHTSA-certified testing lab." Not certified BY NHTSA, but we hired some people who once did some work for NHTSA. Uh huh...
posted
Another thing that bugs the heck out of me with booster seats is I'm supposed to buckle them in even when the kids aren't in the car, because in a crash they might become projectiles. So that means that when I'm alone, I have to crawl in the back and strap down all the empty booster seats (I have three.)
It's a conspiracy, I tell you. I think the car seat manufacturers have been sliding some under the table to the NHTSA - I don't see why a simple, inexpensive seat belt adjustor can't be an ideal solution for kids six and older. But why sell belt positioners for $6.95 a pair when you can charge a mom 80 bucks for a booster seat?
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posted
There's a new law of the "8 or 80 lb" variety that is supposed to go into effect later this year, if I remember correctly. Emily would be exempt since she's now eight, but I'll still have to put up with the younger children.
Bob, what about crossing state lines? I don't know what the laws are in the states we'll be driving through on our vacation. Right now, it is legal for all of my kids to be out of booster seats and if I can get some of those belt adjustors I was going to leave the booster seats behind in Alabama. But if I get pulled over in a different state, am I going to be in trouble if they have one of the 8 or 80 laws?
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posted
Usually if you're a tourist they won't call you on it if your kids are at least 6. Heck, I don't see a lot of people getting pulled over for it in CA and their kids are obviously 5 or 6 and they have in-state plates.
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posted
Here's a site with a map and links for car seat laws by state. (Although some are apparently outdated.)
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posted
Upon reading CA law, it says nothing about a booster seat; it refers to a "child restraint system that conforms with Federal requirements". I would think that belt positioners might qualify; any insights, anyone?
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posted
Wow, that's really cool, kq. Unfortunately, Abigail is not 50 pounds, so that positioner wouldn't be recommended for her. But try telling her that she's the only one of the three kids who has to stay in a booster seat!
I have a friend who has a child in middle-school who still, according to the guidelines, needs to be in a booster seat. As she says, try telling a kid going into junior high she still needs a baby seat!
I'm not trying to dismiss safety concerns, of course I want my kids safe and my husband sees kids who aren't restrained seriously injured all the time. But in his anecdotal experience, he believes also that kids Emily's age do just fine in regular seat belts. The key is to have some sort of restraint - most fatalities are from vehicle ejections, at least of the crashes he sees. I know that's anecdotal, not scientific evidence, but still I think the booster seat laws on older kids is overkill.
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I think the concern is for proper restraint. I don't know what most cops will do if they stop you and your kids are belted and the belt is adjusted properly. I do know that there are some who will cite you for improper restraint because they take seriously and the law says "X".
If I had to deal with this personally, I would write to legislators and the governor to see if I couldn't get the law to make more sense for my situation, whatever it was. And in the meantime, or if that didn't work, I'd just obey the law because it's cheaper and I hate being pulled over for stuff like this.
As I said, though, I haven't seen or looked at data comparing boosters to belt adjusters. I don't think NHTSA is "lobbyable" in the ways that would make it impossible for adjusters to be considered legal and effective if there are data to that effect. NHTSA can't just ignore the data and get away with it when setting policy.
But if there IS data to say that boosters work, and there's no data (or data that can be dismissed) with regard to adjusters, then NHTSA does have a responsibility to promote those things that they know will work.
Ultimately, though, it's up to each state legislature whether they pass mandatory booster seat laws. NHTSA (and others) just recommends what the laws should say.
And, of course, Congress can make funds available or not depending on whether a state has certain laws. They do that by setting requirements for eligibility for NHTSA (and other) grant fund programs.
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posted
I would note that they had a really large 95% confidence interval, from 0.54 to 0.97. That is to say, "We're almost certain it's at least a 3% effect." For such a large error, I think a lower bound is a better way to quote it than the central value.
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posted
Or you can state that the effectiveness is somewhere between 3% and (what was the high end?) 53%?
I must've missed that in the abstract. Too tired to go look at it again.
It's not typically required to report the lower bound, and I don't know of any rule that would say "we should use the lower bound when the range is bigger than "x"
Central tendency is what it is.
Statistical significance is what it is.
But I really want to look at this methods section now, and get a gander at their results tables too.
Thanks for pointing it out, KoM.
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posted
You will please note that I did not say anything about a rule; I said "I think a better way is..." I think a lower bound would just better reflect what their data actually shows. I was also using particle physics standards, which are a touch more stringent than what's common in medicine and the social sciences; it helps, of course, that we have millions, even hundreds of millions, of data points. Much more difficult to arrange with human subjects! But at any rate, by those standards I don't think this result would be published at all; it's only a two-sigma effect. At three sigma, you are permitted to call it an 'indication'. It doesn't become a full-fledged 'observation' until you have five sigma.
EDIT : Actually, I take that back, it could have been published as "Search for", and the conclusion would be "worth investigating, more data needed".
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And no one would ever choose the lower bound over the mean. It's difficult enough getting people to report the confidence intervals around estimates.
It does make for some serious problems with people's undestanding of what's going on in traffic safety.
Sad, but true.
And, really, with the number of data points you have, you'd have to go with p < .00001 or something. You've just got way too much statistical power.
which, btw, is another concept people fail to grasp sufficiently and they start reporting insigificant significant results.
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posted
Yes, that was the problem back in the sixties that led to the five-sigma rule. It used to be three sigma. Posts: 10645 | Registered: Jul 2004
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It's a conspiracy, I tell you. I think the car seat manufacturers have been sliding some under the table to the NHTSA - I don't see why a simple, inexpensive seat belt adjustor can't be an ideal solution for kids six and older. But why sell belt positioners for $6.95 a pair when you can charge a mom 80 bucks for a booster seat?
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