经济与社会科学2020privpapers.ssrn.com
儿童安全座椅作为避孕手段
Car seats as contraception
专业 · 约 80 分钟读完前置知识：计量经济学、因果推断、人口统计基础
导读
这篇论文研究儿童安全座椅强制法规是否通过提高多孩家庭的用车成本（例如一辆车难以放下三个安全座椅）而压低生育率。作者用人口数据并控制多种因素来分离法规影响，估算2017年法规只避免了57名儿童车祸死亡，却使当年出生数减少约8000，1980年以来累计少出生约14.5万人。
HN 关注点：它把一项儿童安全法规与生育率下降联系起来，而“救57条命 vs 少8千个出生”的数字对比尤其引发伦理和方法论争议。
HN 评论精选
这几条评论里：质疑 3 亲历 1
质疑质疑方法：遗漏变量无法穷尽，t统计量不能证明因果，方法描述粗糙。
我读完了原论文，不太理解他们的方法。看起来他们拿了一大堆人口统计信息，然后试图控制所有其他可能影响生育率的因素，以分离出安全座椅法的影响。我怀疑这根本不可能控制所有变量。即使假设他们完美建模了所纳入的因素，也完全可能存在更多未纳入的底层因素。此外，把结果解释成t统计量并不能说明太多问题，因为模型与现实的偏差很可能只是控制变量带来的噪声，而不是安全座椅法与生育率之间的关系。我不是说这篇论文毫无价值——这个想法挺有意思。只是鉴于方法描述很差（且极易出错），我对从结果中推断任何结论都持怀疑态度。
pkage查看英文原文
I read through the underlying paper, and I don't quite understand their methodology. It seems like they're taking a bucketload of demographic information and then trying to control for every other possible factor that could affect fertility rates to isolate the effect of car seat laws. I'm skeptical that it's even possible to control for all of those variables. Even assuming that they perfectly model the factors they do account for, it's perfectly possible that there are more underlying factors. Additionally, interpreting the results as t-statistics doesn't really tell us very much, as the variation between model and reality could easily be noise from the control variables rather than from a relationship between car seat laws and fertility. I'm not saying the paper doesn't have any merit at all--I think the idea is quite interesting. I am just skeptical of inferring anything from the results, given that the methodology is very poorly described (and is so error-prone).
质疑数字对比在伦理上不可比；日本农村亲历显示执行低、事故率低。
> 我们估计，这些法律在2017年全国仅避免了57名儿童车祸死亡。同时，它们导致同年出生数永久减少约8000，自1980年以来少出生14.5万人，其中90%的下降发生在2000年以后。 讽刺……但“本可能出生的孩子”和“事故中失去的生命”完全不可相提并论。 稍微跑题地说，我住在日本农村，在我的经验里大多数孩子乘车不用安全座椅。实际上3到6岁的小孩常常不系安全带，而是站在座位之间或坐在大人腿上。那里显然有儿童座椅法，但似乎很多人无视。我觉得一大原因是事故率更低，因为开车更小心。
dwg查看英文原文
> We estimate that these laws prevented only 57 car crash fatalities of children nationwide in 2017. Simultaneously, they led to a permanent reduction of approximately 8,000 births in the same year, and 145,000 fewer births since 1980, with 90% of this decline being since 2000 Ironic... but a would-be birth vs. loss of life in an accident are immeasurably different things; incomparable. As an slightly off-topic aside, I live in a rural area of Japan where, in my experience, most kids ride without car seats. In fact, small children around 3 to 6 often don't use seatbelts, instead standing between the seats or sit on an adults lap. There is a apparently a child seat law, but it seems a large number of people ignore it. I think the big reason is a lower accident rate, due to more careful driving.
亲历亲历三座椅装车难，直接左右家庭车型选择。
我先有一个孩子，然后是双胞胎，感觉自己被直接扔进了这个问题。带着安全座椅去奔驰经销商时我很震惊：即使不用ISOFIX，E级车也装不下三个座椅。我记得其中两个还是婴儿座椅，这让情况更糟。最后我们选了沃尔沃V70。我们不想要MPV或SUV。
cs02rm0查看英文原文
I had one child and then twins, so I felt like I was just dropped into this. I was pretty shocked turning up with car seats at a Mercedes dealership to find we couldn't get three of them across an E class even without using ISOFIX. IIRC it was slightly exacerbated by two of them being seats for babies. FWIW we went with a Volvo V70. We didn't want an MPV or SUV.
质疑安全座椅还防重伤，法规有实际益处；真正阻碍多孩的是购车成本，“57死”论证站不住。
我们找了很久才找到后排能放下三个安全座椅的车。（注意，我们说的是欧洲车；在北美选择可能更多。）不过只多花了一点时间，因为我们不想要（小）厢式车；如果也考虑厢式车，选择会多得多，而且往往比其它（宽敞）车型更便宜。我理解不是每个人都买得起新车——但如果这是你多要孩子的障碍，我认为原因不是安全座椅要求，而是成本考虑。这很合理。我不接受“只救57名儿童死亡”的论证——除了伦理上可疑，死亡并不是唯一要防止的事情：严重非致命伤害呢？安全座椅强制（且受监管）不是因为有一个强大的安全座椅游说团体，而是因为它们有实际好处。比如，给身高不够的儿童系安全带，风险是安全带会勒到脖子而不是横过胸部，碰撞时这绝不是你想要的。不用是火箭外科医生也能看出这篇论文的叙事可疑。作为父母，我很难想象一对夫妇会说：“要不是这该死的安全座椅问题，我们多想生第三个孩子啊……”
kleiba查看英文原文
We looked around for quite some time before we found a car that fits three car seats in the back. (Mind you, we're talking European cars here, there's a chance our options would have been greater in North America.) However, it only took us a little longer because we weren't keen on a (mini) van -- had we considered vans too, there would have been a lot more options, and they're often even more affordable than other types of (spacious) cars. I understand that not everyone can afford to go out and buy a new car -- but if that is in your way of having more children, I'd say the reason was not the car seat requirement but cost considerations. And I think that's very much a reasonable consideration. I don't buy the "only 57 child deaths" argument - besides obviously being ethically questionable, deaths is not the only thing you want to prevent: how about (severe) non-lethal injuries? The reason car seats are mandatory (and regulated, too) is not because there is a strong car seat lobby but because of the merits they provide. For instance, buckling up a child that isn't tall enough yet bears the risk of getting the belt wrapped around their neck instead of across their chest which in case of an impact is certainly not what you want. You don't have to be a rocket surgeon to find the narrative of this paper questionable. Being a parent myself, I find it very hard to imagine a couple going: "Oh, we would so love to have a third child if it wasn't for that dang car seat problem..." Not that it's completely inconceivable but, I mean, come on...
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