TEDGlobal 2005
Steven Levitt: Surprising stats about child carseats
Steven Levitt 對兒童汽車座椅的研究
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Steven Levitt分享了他對於兒童汽車座椅的研究數據。數據顯示，在降低兒童的車禍死亡率方面，汽車座椅並不比安全帶的效果好。但在自由問答環節裏，他卻發出了一個極其重要的警告。
Steven Levitt - Economist
Steven Levitt's eye-opening Freakonomics took economic theory into the real world of suburban parenting and urban drug gangs, turning conventional wisdom upside-down. Full bio
Steven Levitt's eye-opening Freakonomics took economic theory into the real world of suburban parenting and urban drug gangs, turning conventional wisdom upside-down. Full bio
Double-click the English transcript below to play the video.
00:18
Once upon a time, there was a dread disease that afflicted children.
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很久以前，一種很可怕的疾病曾經困擾著很多兒童
00:23
And in fact, among all the diseases that existed in this land,
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事實上，在目前人類所知的疾病中，
00:27
it was the worst. It killed the most children.
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那是最惡劣的一種病。它奪去了大多數兒童的生命。
00:30
And along came a brilliant inventor, a scientist,
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有這麼一位聰明的發明家，也是個科學家，
00:33
who came up with a partial cure for that disease.
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他研究出一種方法，能在一定程度上治愈這種疾病。
00:36
And it wasn't perfect. Many children still died,
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該方法並非盡善盡美。依然有很多兒童身亡。
00:40
but it was certainly better than what they had before.
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不過，肯定比之前的情況要好得多。
00:43
And one of the good things about this cure was that it was free,
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這種方法最大的好處是免費，
00:49
virtually free, and was very easy to use.
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幾乎是免費，而且使用簡單。
00:51
But the worst thing about it was that you couldn't use it
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但這種方法的缺點是你不能
00:54
on the youngest children, on infants, and on one-year-olds.
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用在小孩子，比如說嬰兒或者一歲大的孩子身上。
00:58
And so, as a consequence, a few years later,
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結果幾年以後，
01:00
another scientist -- perhaps maybe this scientist
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另外一名科學家，這位科學家可能
01:02
not quite as brilliant as the one who had preceded him,
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沒有像他之前那位那麼聰明，
01:06
but building on the invention of the first one --
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但在前輩的發明基礎上
01:08
came up with a second cure.
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他研究出了第二種方法。
01:11
And the beauty of the second cure for this disease
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第二種方法的優點
01:14
was that it could be used on infants and one-year-olds.
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是你可以將其用於嬰兒和一歲大的兒童身上。
01:18
And the problem with this cure was it was very expensive,
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但這個方法有一個問題：那就是非常昂貴，
01:23
and it was very complicated to use.
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而且使用起來非常複雜。
01:24
And although parents tried as hard as they could to use it properly,
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雖然家長們竭盡全力依照正確的方法來使用，
01:28
almost all of them ended up using it wrong in the end.
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但絕大數的家長最後還是不得要領。
01:32
But what they did, of course, since it was so complicated and expensive,
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所以他們的做法是，當然，因為這方法複雜而又昂貴，
01:35
they only used it on the zero-year-olds and the one-year-olds.
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他們僅將其用在零歲和一歲大的兒童。
01:38
And they kept on using the existing cure that they had
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而繼續使用以前的老方法來針對
01:41
on the two-year-olds and up.
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兩歲和兩歲以上的兒童
01:42
And this went on for quite some time. People were happy.
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這種情況持續了很長一段時間。人們還算滿意。
01:44
They had their two cures. Until a particular mother,
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他們有兩種方法可以用。直到有一位母親，
01:47
whose child had just turned two, died of this disease.
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她的孩子在剛满兩歲的時候死於這種疾病。
01:52
And she thought to herself, "My child just turned two,
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她就想說：“我的孩子才剛剛兩歲，
01:56
and until the child turned two, I had always used
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時至今日，我一直都在使用
02:00
this complicated, expensive cure, you know, this treatment.
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這個複雜昂貴的方法，這種治療方案。
02:05
And then the child turned two, and I started using
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而當孩子到了兩歲的時候，我就換成了
02:06
the cheap and easy treatment, and I wonder" --
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另外一個便宜簡單的療法。我想知道……（如果我沒換的話）”
02:09
and she wondered, like all parents who lose children wonder --
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她的想法跟所有那些失去孩子的父母一樣，
02:11
"if there isn't something that I could have done,
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“……是否我真的無力回天，
02:13
like keep on using that complicated, expensive cure."
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比如繼續使用那個這種複雜昂貴的方法。”
02:17
And she told all the other people, and she said,
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她奔走相告，她說，
02:20
"How could it possibly be that something
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“便宜怎麼能有好貨呢？這個東西
02:22
that's cheap and simple works as well as something
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又便宜又簡單，它的效果怎麼可能
02:25
that's complicated and expensive?"
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跟那種昂貴又複雜的一樣呢？
02:27
And the people thought, "You know, you're right.
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人們就想了：“沒錯，言之有理。
02:29
It probably is the wrong thing to do to switch
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改用那個便宜簡單的治療方法，
02:31
and use the cheap and simple solution."
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沒准就是個錯誤。”
02:34
And the government, they heard her story and the other people,
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聽聞此事，政府站了出來
02:37
and they said, "Yeah, you're right, we should make a law.
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說：“是啊。你們說得都對。我們應該制定一條法律。
02:40
We should outlaw this cheap and simple treatment
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我們應該剥奪這個便宜簡單治療方案的合法使用權，
02:42
and not let anybody use this on their children."
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禁止任何人將其用在他們孩子身上。"
02:45
And the people were happy. They were satisfied.
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這樣一來，皆大歡喜.
02:47
For many years this went along, and everything was fine.
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許多年過去了，諸事順利。
02:50
But then along came a lowly economist, who had children himself,
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然後有一位行事低調的經濟學家出現了。他自己本身有孩子，
02:55
and he used the expensive and complicated treatment.
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他用的是那個昂貴複雜的方法。
03:02
But he knew about the cheap and simple one.
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但是他同時也了解那個便宜簡單的方法。
03:04
And he thought about it, and the expensive one
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他覺得那個貴的方法
03:06
didn't seem that great to him. So he thought,
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對他來說好像不那麼完美。於是他就想：
03:09
"I don't know anything about science, but I do know something about data,
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“我對科學一窍不通，但是我對研究數據很在行，
03:12
so maybe I should go and look at the data
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也許我應該搜集一些數據
03:14
and see whether this expensive and complicated treatment
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來研究一下究竟那個昂貴複雜的療法，
03:18
actually works any better than the cheap and simple one."
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是不是真的比那個便宜簡單的好。”
03:21
And lo and behold, when he went through the data,
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嘿，真想不到，當他翻閱了所有數據之後
03:23
he found that it didn't look like the expensive, complicated
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發現那個昂貴複雜的
03:26
solution was any better than the cheap one,
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方法並非真的就比便宜的那個有效。
03:29
at least for the children who were two and older --
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最起碼對於那些兩歲和兩歲以上的孩子來說是這樣的。
03:31
the cheap one still didn't work on the kids who were younger.
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那個便宜的方法還是不適用於更小的兒童（所以無法比較）。
03:34
And so, he went forth to the people and he said,
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於是他就跑去告訴人們。他說，
03:38
"I've made this wonderful finding:
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“我有一個驚人的發現,
03:40
it looks as if we could just use the cheap and simple solution,
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看起來，如果我們只使用那個便宜簡單的療法，
03:43
and by doing so we could save ourselves 300 million dollars a year,
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每年可以節省三億美元。
03:46
and we could spend that on our children in other ways."
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我們可以用這筆錢為孩子做其它的事情。”
03:48
And the parents were very unhappy, and they said,
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結果家長們很不高興，他們說，
03:52
"This is a terrible thing, because how can the cheap and easy thing
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“這簡直是危言聳聽。一個便宜簡單的東西怎麼可能
03:54
be as good as the hard thing?" And the government was very upset.
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跟一個複雜的東西媲美呢？" 政府知道之後也很不爽，
03:58
And in particular, the people who made this expensive solution
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特別是那些利用這個昂貴方法賺錢的人們
04:01
were very upset because they thought,
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就更不爽了。因為他們的想法是：
04:03
"How can we hope to compete with something that's essentially free?
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“我們怎麼可能有希望跟那些幾乎免費的東西競爭呢？
04:06
We would lose all of our market."
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我們將會失去全部的市場份額。”
04:08
And people were very angry, and they called him horrible names.
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人們很憤怒，把他罵了一個狗血噴頭。
04:11
And he decided that maybe he should leave the country
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無奈，他決定離開這個國家
04:14
for a few days, and seek out some more intelligent,
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一段時間，去到一個地方找尋其他更有智慧，
04:18
open-minded people in a place called Oxford,
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思想更開明的人。這個地方叫做牛津。
04:21
and come and try and tell the story at that place.
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他去到那裏，試圖把這件事情講給人們聽。
04:24
And so, anyway, here I am. It's not a fairy tale.
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所以，總而言之。我的意思是，這並非一個童話。
04:28
It's a true story about the United States today,
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這是發生在當今美國的真事。
04:30
and the disease I'm referring to is actually
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而我所提到的疾病實際上是
04:33
motor vehicle accidents for children.
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車禍，跟兒童相關的車祸。
04:36
And the free cure is adult seatbelts, and the expensive cure --
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這個免費的療法就是成年人使用的安全帶，而那個昂貴的療法，
04:42
the 300-million-dollar-a-year cure -- is child car seats.
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那個三億美元一年的療法，則是兒童汽車座椅。
04:46
And what I'd like to talk to you about today
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今天我想跟你分享的是
04:48
is some of the evidence why I believe this to be true:
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一些證明我觀點正確的事實證據：
04:51
that for children two years old and up,
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那就是對於兩歲和兩歲以上的兒童來說，
04:53
there really is no real benefit -- proven benefit -- of car seats,
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汽車座椅真的不起作用，我指的是沒有證據可以證明其有用。
04:58
in spite of the incredible energy
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盡管大量的精力
05:03
that has been devoted toward expanding the laws
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都投入到了積極推廣汽車座椅安全的法規中，
05:06
and making it socially unacceptable
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從而使讓儿童只使用安全帶
05:08
to put your children into seatbelts. And then talk about why --
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變成不被社會認可的行為。讓我們談一下為什麼，
05:13
what is it that makes that true?
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是什麼讓這一觀點變為既成事實？
05:14
And then, finally talk a little bit about a third way,
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最後，我們要談一下第三種（保護儿童）方法，
05:17
about another technology, which is probably better than anything we have,
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另外一種可能比目前任何方法都先進的科技，
05:20
but which -- there hasn't been any enthusiasm for adoption
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但人們還沒有多大兴趣采用，
05:23
precisely because people are so enamored
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準確地講，因為人們過於傾心於
05:25
with the current car seat solution. OK.
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兒童汽車座椅這個方案。好的。
05:28
So, many times when you try to do research on data,
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很多時候，當你試圖進行數據研究的時候，
05:31
it records complicated stories -- it's hard to find in the data.
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裏面記錄了一些具有複雜背景的事件。你很難從這些數據中找到你想要的東西，
05:35
It doesn't turn out to be the case when you look at seatbelts versus car seats.
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或者說其結果並非如你所願，就好象比較安全帶跟兒童汽車座椅哪個更好。
05:38
So the United States keeps a data set
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美國政府保留了一份數據。
05:40
of every fatal accident that's happened since 1975.
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其中包含了從1975年至今每一個致命死亡事故。
05:43
So in every car crash in which at least one person dies,
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每發生一次車禍，就至少有一人死亡。
05:46
they have information on all of the people.
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他們記錄了所有這些車祸當事人的信息。
05:48
So if you look at that data -- it's right up on the National Highway
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所以你可以瀏鑒一下這些數據。這些數據發布在全美高速公路
05:51
Transportation Safety Administration's website --
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交通安全局的網頁上。
05:53
you can just look at the raw data,
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通過這些原始數據，
05:55
and begin to get a sense of the limited amount of evidence
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你可以發現支持兩歲和兩歲以上兒童使用汽車座椅
05:59
that's in favor of car seats for children aged two and up.
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的證據非常有限。
06:02
So, here is the data. Here I have, among two- to six-year-olds --
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這是我手裏的數據。這裏顯示兩歲到六歲，
06:06
anyone above six, basically no one uses car seats,
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基本來說六歲以上的兒童就不需要使用汽車座椅了。
06:08
so you can't compare -- 29.3 percent of the children who are unrestrained
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因此，你可以比較一下。 在每次車禍必死一人的情況下，
06:14
in a crash in which at least one person dies, themselves die.
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沒有使用保護措施的孩子的死亡率為29.3%。
06:18
If you put a child in a car seat, 18.2 percent of the children die.
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如果你把孩子放進汽車座椅中，其死亡率是18.2%。
06:23
If they're wearing a lap-and-shoulder belt, in this raw data,
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如果他們系了腰及肩的安全帶，根據這個原始數據，
06:25
19.4 percent die. And interestingly, wearing a lap-only seatbelt,
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死亡率是19.4%. 有意思的是，如果只系腰部安全帶，
06:30
16.7 percent die. And actually, the theory tells you
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死亡機率是16.7%。事實上，原則上來說，
06:32
that the lap-only seatbelt's got to be worse
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這種只護腰部的安全帶的效果比
06:35
than the lap-and-shoulder belt. And that just reminds you
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腰及肩的安全更糟。而且我還要提醒你的是，
06:36
that when you deal with raw data, there are hundreds
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當你在研究原始數據時，這裏有成百上千
06:38
of confounding variables that may be getting in the way.
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的變量因素混淆其中，從而影響到最終結果。
06:41
So what we do in the study is -- and this is just presenting
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所以我們換一種方式來看待這個問題，這裏使用的是
06:46
the same information, but turned into a figure to make it easier.
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相同的數據，但變成了圖表後看起來簡單明了。
06:49
So the yellow bar represents car seats,
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黃色條塊代表了汽車座椅（兒童的死亡率），
06:52
the orange bar lap-and-shoulder, and the red bar lap-only seatbelts.
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桔色條塊代表了腰及肩的安全帶（兒童的死亡率），而紅色條塊則代表了僅護腰的安全帶（兒童的死亡率）。
06:56
And this is all relative to unrestrained --
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這些條塊已經跟無保護措施（兒童的死亡率）的情況作過比較了。
06:58
the bigger the bar, the better. Okay.
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色塊越大越好。好的。
06:59
So, this is the data I just showed, OK?
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左邊是我剛剛展示過的數據，對吧？
07:01
So the highest bar is what you're striving to beat.
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最高的那個色塊就是人們死活不願意認同的。
07:04
So you can control for the basic things, like how hard the crash was,
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你可以考慮到該研究中最基本的因素，比如車禍的嚴重性有多大，
07:08
what seat the child was sitting in, etc., the age of the child.
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孩子坐在哪個位置上，等等 。還有孩子的年齡。
07:12
And that's that middle set of bars.
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那結論就是中間那一組色塊。
07:14
And so, you can see that the lap-only seatbelts
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你可以發現僅護腰的安全帶，
07:17
start to look worse once you do that.
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開始看起來不安全了。
07:19
And then finally, the last set of bars,
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最終，最右邊這組色塊，
07:21
which are really controlling for everything
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是在考慮到所有可能性之後而得出的結論。
07:24
you could possibly imagine about the crash,
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你可以想像任何一種車禍。
07:26
50, 75, 100 different characteristics of the crash.
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五十種，七十五種，一百種不同性質的車祸。
07:29
And what you find is that the car seats and the lap-and-shoulder belts,
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你會發現，使用汽車座椅和腰及肩安全帶，
07:32
when it comes to saving lives, fatalities look exactly identical.
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在救命方面而言，其死亡率看起來毫無二致。
07:36
And the standard error bands are relatively small around these estimates as well.
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而且有關這些估算值的標準誤差範圍相對也比較小。
07:40
And it's not just overall. It's very robust
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這不僅是泛泛而談，這個結論適用於
07:43
to anything you want to look at.
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任何一種車禍。
07:45
One thing that's interesting: if you look at frontal-impact crashes --
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有一件事很有趣：如果你看一下正面衝撞的車祸，
07:48
when the car crashes, the front hits into something --
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車禍發生時，車頭撞向某一處，
07:51
indeed, what you see is that the car seats look a little bit better.
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汽車座椅看起來確實更好一點兒。
07:55
And I think this isn't just chance.
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但我認為這其中必有原由。
07:57
In order to have the car seat approved,
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如果汽車座椅的生產想要通過許可，
07:58
you need to pass certain federal standards,
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就必須達到一定的聯邦標準，
08:01
all of which involve slamming your car into a direct frontal crash.
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而這些都假設你的車頭發生正面衝撞。
08:06
But when you look at other types of crashes, like rear-impact crashes,
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但是當你看看其它類型的車禍，比如追尾，
08:08
indeed, the car seats don't perform as well.
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汽車座椅其實根本不起作用。
08:11
And I think that's because they've been optimized to pass,
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我想這是因為他們都是針對車頭正面沖撞來設計的。
08:13
as we always expect people to do,
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就象大家經常會做的，
08:15
to optimize relative to bright-line rules
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上有政策，下有對策，
08:17
about how affected the car will be.
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在汽車安全這一問題上也是一樣。
08:21
And the other thing you might argue is,
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你可能會提出另外一個觀點，
08:22
"Well, car seats have got a lot better over time.
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汽車座椅的安全性能變得越來越好。
08:24
And so if we look at recent crashes --
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如果我們看看最近發生的車禍
08:27
the whole data set is almost 30 years' worth of data --
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這裏包含了幾乎過去30年的全部數據，
08:29
you won't see it in the recent crashes. The new car seats are far, far better."
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但你看不到有關汽車座椅的事故。新型汽車座椅的設計遠遠好於以前舊的。
08:31
But indeed, in recent crashes the lap-and-shoulder seatbelts,
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但實際上，在最新的車禍數據中，腿及肩安全帶
08:35
actually, are doing even better than the car seats.
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的表現甚至比汽車座椅還要好。
08:38
They say, "Well, that's impossible, that can't be."
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人們會說，“哦，這不可能，完全不合邏輯。“
08:41
And the line of argument, if you ask parents, is,
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如果你問一下這些父母，他們爭論的重點集中在
08:43
"But car seats are so expensive and complicated,
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“汽車座椅那麼貴那麼複雜，
08:46
and they have this big tangle of latches,
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還有一大堆這樣那樣的鎖扣，
08:49
how could they possibly not work better than seatbelts
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它們怎麼可能沒有安全帶好呢？
08:52
because they are so expensive and complicated?"
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因為它們又貴又複雜！”
08:54
It's kind of an interesting logic,
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這是一個很有趣的邏輯，
08:57
I think, that people use. And the other logic, they say,
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我覺得，他們把它用在這裏。至於其它的邏輯，他們說，
09:00
"Well, the government wouldn't have told us [to] use them
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“哦，如果安全帶更好的話，
09:02
if they weren't much better."
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政府不會毫無理由地不讓我們用。”
09:04
But what's interesting is the government telling us to use them
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但有意思的是，政府鼓勵我們去使用
09:06
is not actually based on very much.
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並不能成為真正的理論基礎。
09:08
It really is based on some impassioned pleas of parents
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這是基於某些父母的強烈請求,
09:11
whose children died after they turned two,
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而這些父母的孩子在剛兩歲的時候就死於車禍，
09:14
which has led to the passage of all these laws -- not very much on data.
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這才使得法規得以通過，而並非是以事實數據為基准而得到的結論。
09:18
So you can only get so far, I think, in telling your story
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到目前為止，我只能用這些抽象的統計數據
09:22
by using these abstract statistics.
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讓你了解這麼多。
09:24
And so I had some friends over to dinner, and I was asking --
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當我請朋友們來家裏吃飯時，我問他們，
09:29
we had a cookout -- I was asking them what advice they might have for me
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我們當時在露天燒烤，我想聽聽他們的建議，我要如何做才能
09:32
about proving my point. They said, "Why don't you run some crash tests?"
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進一步證明我的觀點。他們說：“為什麼你不做一些撞車試驗？”
09:36
And I said, "That's a great idea."
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我說：“這是個很好的主意。”
09:38
So we actually tried to commission some crash tests.
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於是，我們試圖委託其它機構幫我們進行測試，
09:40
And it turns out that as we called around to the independent
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結果是，我們給全國的獨立
09:45
crash test companies around the country,
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撞車測試機構打了一圈電話，
09:48
none of them wanted to do our crash test
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沒有人願意接手。
09:50
because they said, some explicitly, some not so explicitly,
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因為他們說， 有的直言不諱，有的拐彎磨角，
09:54
"All of our business comes from car seat manufacturers.
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“我們的生意都來源於汽車座椅生產廠家。
09:56
We can't risk alienating them by testing seatbelts relative to car seats."
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我們無法冒著得罪他們的風險，來做安全帶跟汽車座椅的比較測試。”
10:00
Now, eventually, one did. Under the conditions of anonymity,
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後來終於有一家公司答應了。他們說，在透露他們身份的條件下，
10:04
they said they would be happy to do this test for us --
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他們很高興幫我們這個忙。
10:07
so anonymity, and 1,500 dollars per seat that we crashed.
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於是以匿名為前提，每撞毀一個座椅我們支付他們1,500美元。
10:12
And so, we went to Buffalo, New York,
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我們前往紐約水牛城（去做這個測試）。
10:14
and here is the precursor to it.
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這是測試之前的情況。
10:16
These are the crash test dummies,
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這是用於測試的人體模型，
10:18
waiting for their chance to take the center stage.
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正在等著機會登場。
10:21
And then, here's how the crash test works.
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這裏你可以看到我們是如果進行撞車測試的。
10:23
Here, they don't actually crash the entire car, you know --
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這裏，他們並非把整輛車撞毀，你知道，
10:26
it's not worth ruining a whole car to do it.
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為了做測試而毀掉一整輛車是不劃算的。
10:29
So they just have these bench seats,
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所以，你必須用這些長條座椅，
10:30
and they strap the car seat and the seatbelt onto it.
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然後把汽車座椅和安全帶安裝在上面。
10:32
So I just wanted you to look at this.
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我想讓你看一下這個景象。
10:34
And I think this gives you a good idea of why parents think
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我想這能給你一個理由為什麼父母們認為
10:36
car seats are so great. Look at the kid in the car seat.
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汽車座椅如此之好。看看汽車座椅裏的孩子。
10:38
Does he not look content, ready to go,
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他看上去不是很舒服，時刻準備出發，
10:41
like he could survive anything? And then, if you look at the kid in back,
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好象不管什麼事故發生他都會安然無恙嗎？但如果你看一下坐在後座的那個孩子，
10:43
it looks like he's already choking before the crash even happens.
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好象車禍還沒發生，他就已經快要窒息了。
10:46
It's hard to believe, when you look at this, that
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看到這裏，你很難相信
10:49
that kid in back is going to do very well when you get in a crash.
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一旦車禍發生，坐在後面的那個孩子能夠完好無損。
10:51
So this is going to be a crash
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碰撞實驗開始時，
10:53
where they're going to slam this thing forward into a wall
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他們會把這個裝置使勁地摔到前面的墙上，
10:56
at 30 miles an hour, and see what happens. OK?
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速度是每小時30英哩。讓我們看看會發生什麼。好嗎？
10:59
So, let me show you what happens.
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請允許我展示給你。
11:01
These are three-year-old dummies, by the way.
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對了，這些是模仿3歲兒童的人體模型。
11:04
So here -- this is the car seat. Now watch two things:
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這裏是汽車座椅（和坐在裏面的孩子）。現在請注意兩件事情。
11:06
watch how the head goes forward,
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注意模型的頭向前猛沖，
11:08
and basically hits the knees -- and this is in the car seat --
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基本上撞到自己的膝蓋，這是坐在汽車座椅裏的孩子的情況。
11:10
and watch how the car seat flies around, in the rebound, up in the air.
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再者，注意觀察汽車座椅空中反彈後，
11:15
The car seat's moving all over the place.
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飛來飛去。
11:17
Bear in mind there are two things about this.
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請記住，這裏面有兩個因素。
11:19
This is a car seat that was installed by someone
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安裝這個汽車座椅的人
11:22
who has installed 1,000 car seats, who knew exactly how to do it.
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之前已經安裝過上千個了，他準確地知道如何去做。
11:25
And also it turned out these bench seats
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而且，結果顯示，這些長條座椅
11:26
are the very best way to install car seats.
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是最適合安裝汽車座椅的。
11:29
Having a flat back makes it much easier to install them.
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這個椅子的靠背是平的，所以安裝起來簡單很多。
11:32
And so this is a test that's very much rigged in favor of the car seat,
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這是一個對汽車座椅很有利的測試裝置。
11:35
OK? So, that kid in this crash fared very well.
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是吧？那個（坐在汽車座椅中的）孩子在這次沖撞中的境遇不錯。
11:38
The federal standards are
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按照聯邦標準
11:40
that you have to score below a 1,000
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你危險系數必須少於1,000
11:42
to be an approved car seat on this crash,
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才能通過這類撞車測驗，
11:44
in some metric of units which are not important.
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這裏就不細說危險系數怎麼計算的了。
11:48
And this crash would have been about a 450.
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這個汽車座椅的危險系數應該在450左右。
11:51
So this car seat was actually an above-average car seat
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所以，這實際上是一個高於平均水平的汽車座椅。
11:53
from Consumer Reports, and did quite well.
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在消費者評價中，該座椅的性能很好。
11:55
So the next one. Now, this is the kid, same crash,
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下一個，是這個孩子，相同的測試
11:58
who is in the seatbelt. He hardly moves at all, actually,
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不同的是他使用的是安全帶。實事上，他基本上連動都沒有動，
12:03
relative to the other child. The funny thing is,
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跟剛才那個坐在汽車座椅裏的孩子比起來。有趣的是，
12:06
the cam work is terrible because they've only set it up
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這個錄像很糟糕，因為它們只是被用來
12:09
to do the car seats, and so, they actually don't even have a way
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做汽車座椅測試的，所以你沒辦法把攝像機
12:11
to move the camera so you can see the kid that's on the rebound.
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移到後面，以便看到那個孩子的反彈情況
12:13
Anyway, it turns out that those two crashes, that actually
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總而言之，是在這兩次測試中，那個
12:17
the three-year-old did slightly worse. So, he gets about a 500
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三歲孩子的模型的情況稍差一點兒。所以，他的危險系數得分是500，
12:21
out of -- you know, on this range -- relative to a 400 and something.
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在這個400到1000的範圍內。
12:25
But still, if you just took that data from that crash
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但是，如果你只是把通過撞車測試採集到的這一數據（危險系數500）
12:28
to the federal government, and said, "I have invented a new car seat.
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拿給聯邦政府，然後說：“我發明了一個新的汽車座椅，
12:31
I would like you to approve it for selling,"
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我希望你能批准我銷售它。”
12:34
then they would say, "This is a fantastic new car seat, it works great.
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然後，他們就會說：“這是一個非常出色的新汽車座椅，性能很棒。”
12:37
It only got a 500, it could have gotten as high up as a 1,000."
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它的危險系數只有500，只要不超過1000就行。
12:39
And this seatbelt would have passed with flying colors
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那麼這個安全帶毫無疑問也能通過測試
12:42
into being approved as a car seat.
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並獲得跟汽車座椅一樣的生產許可。
12:44
So, in some sense, what this is suggesting
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所以在某種程度上來說，這表明了
12:46
is that it's not just that people are setting up their car seats wrong,
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人們不僅錯誤地安裝了汽車座椅，
12:49
which is putting children at risk. It's just that, fundamentally,
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讓孩子們的生命受到威脅。而是從根本上來說，
12:51
the car seats aren't doing much.
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汽車座椅的作用並不大。
12:53
So here's the crash. So these are timed at the same time,
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這是另外一個撞車測試，他們在同一時間同步進行。
12:55
so you can see that it takes much longer with the car seat --
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你可以看到，汽車座椅恢復原位所用的時間更長，
12:57
at rebound, it takes a lot longer --
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特別是反彈之後，所有的時間更長。
12:59
but there's just a lot less movement for child who's in the seatbelt.
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但是，系安全帶的那個孩子移動的幅度小得多。
13:03
So, I'll show you the six-year-old crashes as well.
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接下來，我要給你看看針對六歲大孩子的撞車測試。
13:05
The six-year-old is in a car seat, and it turns out
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使用汽車座椅的六歲孩子，其結果
13:10
that looks terrible, but that's great. That's like a 400, OK?
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看上去很恐怖，但其實不錯。這個的危險系數得分大約是400，對吧？
13:15
So that kid would do fine in the crash.
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所以這個孩子在車禍發生時可以安然無恙。
13:16
Nothing about that would have been problematic to the child at all.
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不會有任何事情發生在他身上。
13:20
And then here's the six-year-old in the seatbelt,
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這是一個系安全帶的六歲孩子，
13:23
and in fact, they get exactly within, you know,
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事實上，這兩個測驗的得分幾乎一樣，
13:25
within one or two points of the same. So really, for the six-year-old,
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只有一兩分的差別。說真的，對於六歲的孩子來說，
13:29
the car seat did absolutely nothing whatsoever.
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汽車座椅完全沒有一點兒作用。
13:33
That's some more evidence, so in some sense --
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這裏有更多的數據，在某種程度上，
13:36
I was criticized by a scientist, who said, "You could never publish
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我被一位科學家批评說：“就憑著四個例子，你永遠都不可能發表
13:40
a study with an n of 4," meaning those four crashes.
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任何一個研究結果。” 意思是說我只做了四次撞車測試。
13:42
So I wrote him back and I said, "What about an n of 45,004?"
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我就回信對他說：“如果我有四萬五千零四個例子呢？”
13:46
Because I had the other 45,000 other real-world crashes.
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因為，我手裏有四萬五千零四例的真實車禍。
13:48
And I just think that it's interesting that the idea
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我就想，這個用實際車禍做為依據
13:52
of using real-world crashes, which is very much something
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的主意很有意思。這是那種
13:54
that economists think would be the right thing to do,
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經濟學家們認為理所當然的事情，
13:56
is something that scientists don't actually, usually think --
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而科學家們卻不會，通常他們認為，
13:58
they would rather use a laboratory,
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他們更願意用實驗來說話，
14:01
a very imperfect science of looking at the dummies,
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就象一個用人體模型來做研究的漏洞百出科學實驗，
14:03
than actually 30 years of data of what we've seen
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而不願意使用我們這三十年來所看到
14:07
with children and with car seats.
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跟兒童和汽車座椅相關的真實數據
14:10
And so I think the answer to this puzzle
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所以，我認為，解開迷底的答案
14:14
is that there's a much better solution out there,
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就是還有另外一個更好方法，
14:17
that's gotten nobody excited because everyone
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只不過沒人動心。因為每個人都
14:20
is so delighted with the way car seats are presumably working.
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對汽車座椅所謂的性能感到很滿意。
14:24
And if you think from a design perspective,
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如果你從設計的角度出發，
14:27
about going back to square one, and say,
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回到當初一片空白的階段，然後說：
14:29
"I just want to protect kids in the back seat."
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“我只想保護坐在後座的孩子們。”
14:31
I don't there's anyone in this room who'd say,
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我不認為這個房間裏諸位會說：
14:33
"Well, the right way to start would be,
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“我們應該做的是
14:34
let's make a great seat belt for adults.
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讓我們給成年人設計一個非常棒的安全帶。
14:37
And then, let's make this really big contraption
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然後，我們把這些鏈子拼湊在一起
14:39
that you have to rig up to it in this daisy chain."
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做成一個奇形怪狀的東西。”
14:42
I mean, why not start -- who's sitting in the back seat anyway except for kids?
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我的意思是說，為什麼不從這個角度考慮。如果保護那些坐在後座上的人們，除了孩子之外。
14:45
But essentially, do something like this,
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基本上，做成這樣的東西，
14:48
which I don't know exactly how much it would cost to do,
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我不知道這要花費多大的成本，
14:50
but there's no reason I could see
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但沒理由
14:51
why this should be much more expensive than a regular car seat.
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這會比普通的汽車座椅要貴。
14:53
It's just actually -- you see, this is folding up -- it's behind the seat.
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實際上，你看，這可以折疊起來，翻到座位後面。
14:57
You've got a regular seat for adults, and then you fold it down,
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平時這就是一個正常的成人用的座位，然後把它折下來，
14:59
and the kid sits on top, and it's integrated.
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孩子們就可以坐在上面。這個裝置跟車集成在一起。
15:01
It seems to me that this can't be a very expensive solution,
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對我來說，這似乎不可能是很貴的方案，
15:05
and it's got to work better than what we already have.
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而且這肯定比我們現有要好得多。
15:08
So the question is, is there any hope for adoption of something like this,
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問題是，這樣的東西有沒有希望被接受，
15:13
which would presumably save a lot of lives?
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如果我們假設它可以挽救很多的生命？
15:15
And I think the answer, perhaps, lies in a story.
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我認為答案，有可能在以下的故事中找到。
15:19
The answer both to why has a car seat been so successful,
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這解釋了為什麼汽車座椅如此成功，
15:23
and why this may someday be adopted or not,
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以及為什麼我的發明有一天可能會被接受，也可能不會。
15:26
lies in a story that my dad told me, relating to when he was a doctor
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答案就在以下我爸爸講給我的一個故事裏。他曾經是英國空軍駐軍
15:30
in the U.S. Air Force in England. And this is a long time ago:
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的醫生。而且這是很久以前的事兒了。
15:33
you were allowed to do things then you can't do today.
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那時，你可以有自主權做一些今天不能做的事情。
15:35
So, my father would have patients come in
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那會兒，會有病人來找我父親看病，
15:39
who he thought were not really sick.
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但我爸發現他們並沒有病。
15:42
And he had a big jar full of placebo pills that he would give them,
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他就給病人開滿滿一大罐沒有藥效，純屬安慰性質的藥片，
15:46
and he'd say, "Come back in a week, if you still feel lousy."
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然後說：“如果一星期之內你仍然感覺不好，就回來複診。”
15:49
OK, and most of them would not come back,
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好了，很多人不會回來，
15:50
but some of them would come back.
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也有人會回來複診。
15:52
And when they came back, he, still convinced they were not sick,
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但當他們回來的時候，他還是確信他們沒病，
15:56
had another jar of pills. In this jar were huge horse pills.
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再給他們一大罐藥片。這一罐裏裝的是那種特大的藥片。
16:01
They were almost impossible to swallow.
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這幾乎沒有可能吞下去。
16:03
And these, to me, are the analogy for the car seats.
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而這些，對於我來說，就形同汽車座椅。
16:07
People would look at these and say, "Man, this thing is so big
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人們看著這些藥片會說：“天哪，這個東西這麼大，
16:11
and so hard to swallow. If this doesn't make me feel better,
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這麼難以下咽。如果這都無法治好我，
16:13
you know, what possibly could?"
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你說，還有什麼可以？”
16:16
And it turned out that most people wouldn't come back,
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結果是，大多數的病人都不會回來
16:18
because it worked. But every once in a while,
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如果藥起了作用。但偶爾，
16:21
there was still a patient convinced that he was sick,
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有這麼一兩個病人確信自己病得很厲害，
16:26
and he'd come back. And my dad had a third jar of pills.
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他還會第三次回來。而我爸爸就會拿出第三罐藥片。
16:29
And the jar of pills he had, he said,
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他說，他手裏這罐藥片，
16:31
were the tiniest little pills he could find,
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是那種他可以找到的最微型的，
16:34
so small you could barely see them.
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小到幾乎看不見。
16:36
And he would say, listen, I know I gave you that huge pill,
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他說，聽著，我知道以前我給你開過那種大型藥片，
16:38
that complicated, hard-to-swallow pill before,
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那種複雜，又不容易下咽的藥片。
16:42
but now I've got one that's so potent,
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現在，我有一種非常有效的藥，
16:44
that is really tiny and small and almost invisible.
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但它很小，幾乎看不到。
16:46
It's almost like this thing here, which you can't even see."
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就象這個東西一樣，你甚至無法看到。”
16:49
And it turned out that never,
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結果，再也沒有，
16:51
in all the times my dad gave out this pill, the really tiny pill,
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在我爸把這些很小很小的藥片給出去之後，
16:54
did anyone ever come back still complaining of sickness.
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再也沒有人回來抱怨自己病得很厲害了。
16:57
So, my dad always took that as evidence
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我爸經常拿這個說事兒，
17:00
that this little, teeny, powerful pill
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說這些小得不能再小的強力藥片，
17:04
had the ultimate placebo effect. And in some sense, if that's the right story,
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反而起到的心理慰籍的作用最大。在某種程度上來說，如果這個故事真的說明問題 ，
17:08
I think integrated car seats you will see, very quickly,
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我認為，你很快會看到，這個組合式的汽車座椅
17:10
becoming something that everyone has. The other possible conclusion
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將會成為每個人的必備。另外一個可能的結論
17:14
is, well, maybe after coming to my father three times,
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是，嗯，可能在回來找我父親看過三次病之後，
17:17
getting sent home with placebos, he still felt sick,
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拿著安慰藥片回到家裏，他還是覺得不舒服，
17:19
he went and found another doctor.
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他會去看另外一個醫生。
17:21
And that's completely possible. And if that's the case,
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這是完全有可能的。而且，如果真是這樣的話，
17:23
then I think we're stuck with conventional car seats for a long time to come.
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我認為，在接下來很長一段時間裏，我只好繼續使用傳統的汽車座椅。
17:26
Thank you very much.
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非常感謝。
17:27
(Applause)
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（掌聲）
17:31
(Audience: I just wanted to ask you, when we wear seatbelts
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（觀眾：我只是想問你，當我們系上安全帶的時候，
17:33
we don't necessarily wear them just to prevent loss of life,
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我們並非只是用它防止車禍死亡的發生，
17:36
it's also to prevent lots of serious injury.
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它也是用來防止車禍造成的受傷。
17:38
Your data looks at fatalities. It doesn't look at serious injury.
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你的數據只是針對死亡率，並不包括嚴重受傷的情況。
17:42
Is there any data to show that child seats
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有沒有數據可以顯示汽車座椅在防止受傷方面的，
17:44
are actually less effective, or just as effective as seatbelts
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效果並不明顯，或著沒有安全帶那麼明顯？
17:47
for serious injury? Because that would prove your case.)
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因為這才能證明你的論點。
17:49
Steven Levitt: Yeah, that's a great question. In my data, and in another data set
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是的，這個問題提得很好。在我的數據當中，包括另外一組
17:52
I've looked at for New Jersey crashes,
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針對新澤西撞車試驗所研究的數據，
17:55
I find very small differences in injury.
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我發現兩種措施在減少受傷方面的差異很小。
17:59
So in this data, it's statistically insignificant differences
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在這個數據中，統計學上的差異微乎其微，
18:01
in injury between car seats and lap-and-shoulder belts.
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我是指在受傷方面，汽車座椅跟腰及肩安全帶相比較來說。
18:05
In the New Jersey data, which is different,
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在新澤西的數據中，情況卻有所不同。
18:06
because it's not just fatal crashes,
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因為這不僅只是致命性的車禍，
18:09
but all crashes in New Jersey that are reported,
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而是所有在新澤西進行的撞車測試報告。
18:11
it turns out that there is a 10 percent difference in injuries,
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結果是，在防止受傷方面的差異是百分之十，
18:14
but generally they're the minor injuries.
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總的來說，車禍造成的都是很輕微的損傷。
18:16
Now, what's interesting, I should say this as a disclaimer,
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有意思的是，我應該說，盡管不認同，
18:18
there is medical literature that is very difficult to resolve with this other data,
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有篇醫學文獻用新澤西的數據很難解釋。
18:23
which suggests that car seats are dramatically better.
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這篇文獻顯示，汽車座椅的安全性顯著地好於其它。
18:27
And they use a completely different methodology that involves --
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他們用了一個完全不同的方法論，這包括
18:29
after the crash occurs, they get from the insurance companies
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在撞車發生之後，他們從保險公司手裏拿到
18:32
the names of the people who were in the crash,
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車祸受害者的姓名，
18:34
and they call them on the phone,
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然後打電話給他們，
18:35
and they asked them what happened.
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詢問他們事情的經過。
18:36
And I really can't resolve, yet,
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我目前還解釋不了
18:39
and I'd like to work with these medical researchers
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但我很願意跟一些醫學研究工作者一起合作，
18:41
to try to understand how there can be these differences,
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試圖找出這些差異是如何產生的，
18:44
which are completely at odds with one another.
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簡直一個天上，一個地下。
18:47
But it's obviously a critical question.
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這顯然是個不容忽視的問題。
18:50
The question is even if -- are there enough serious injuries
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問題是，即使，我們有沒有足夠多的車禍重傷的例子
18:53
to make these cost-effective? It's kind of tricky.
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使得我們的研究花費物有所值。這真的很難講。
18:56
Even if they're right, it's not so clear
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就算他們的結果是正確的，我們還是無法弄清
18:58
that they're so cost-effective.
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汽車安全座椅的性價比是不是真的好。
ABOUT THE SPEAKER
Steven Levitt - EconomistSteven Levitt's eye-opening Freakonomics took economic theory into the real world of suburban parenting and urban drug gangs, turning conventional wisdom upside-down.
Why you should listen
With his 2005 book Freakonomics (co-authored with Stephen Dubner, a writer who profiled him for the New York Times), Steven Levitt carried hardcore economic method into the squishy real world and produced a pop-culture classic. Freakonomics is both an economics textbook and a series of cautionary tales about the fallacy of conventional wisdom. Levitt examines the links between real-world events, and finds many instances where the data simply doesn't back up popular belief.
He asks provocative questions: If selling crack is so lucrative, why do dealers live with their mothers? Does parental doting really improve children's test scores? Did New York City's crime rate really drop because of police tactics (or population trends)? His controversial answers stir debate, and sometimes backlash.
Steven Levitt | Speaker | TED.com