PBS高端访谈:教师对学生终身收入的影响

 　　JEFFREY BROWN: And finally tonight, putting a price on the value of good teachers. A large and new study addresses just that.

　　Ray Suarez has the story.

　　RAY SUAREZ: The debate over testing in schools, and whether students' scores adequately reflect a teacher's performance, has been raging for well over a decade. Now a new study has tracked more than two-and-a-half million students over two decades.

　　It found test scores are indeed a good gauge¹ for evaluating student performance. And the study found replacing a bad teacher with an average or a good one can translate into a huge economic difference. Combined, the students could earn hundreds of thousands of dollars more over their working lifetimes.

　　We look at the study and the response it's stirred with Harvard economist² Raj Chetty, one of its three authors. And we hope to be joined by Randi Weingarten, president of the American Federation³ of Teachers, the second largest teachers union.

　　Professor Chetty, how do you measure student performance over such a long period of time? Some of the people in your study are in their late 20s now. And how do you determine it's the teachers who made the difference?

　　RAJ CHETTY, Harvard University: The way we do that is, we track these students from elementary school, so we know what teachers they had in elementary school, and then we look at how they're doing as adults.

　　And the way we measure teacher quality is look at the average impacts that teachers had on the students' test scores, the students that they were teaching. So, for example, a teacher who systematically⁴ raised her students' test scores year after year, we would call that teacher a high-value-added teacher.

　　And a teacher who didn't do as well might be an average- or low-value-added teacher. And so the question we then ask is, suppose you, by chance, were assigned to a high-value-added teacher when you were in fourth grade, and I was less lucky and only got an average-value-added teacher. Are we doing differently as adults? Are we more likely to go to college if we have a higher value-added teacher? Are you more likely to earn a higher salary and so on?

　　And we find remarkable⁵ impacts. Students who were assigned to high-value-added teachers earn more. They're more likely to go to college. They're less likely to have a teenage pregnancy⁶, and they do better on a number of dimensions that we're able to study.

　　RAY SUAREZ: But there are so many variables involved. How do you exclude things like the level of education in the home, the overall achievement of an individual school, what the individual student was doing before they got to that grade and got a standardized⁷ test?

　　RAJ CHETTY: That's an excellent question.

　　In fact, what makes this topic so difficult to study and has been a real challenge in this area, as in the social sciences more generally. So, our approach in this study is to use sort of random⁸ variation in the set of teachers who happen to be around when you arrive in a school.

　　So let me give an example. Suppose, Ray, that you are a year older than me and we both are in the same school and you arrive in fourth grade in 1995, when Mrs. Smith, who let's say is a high-value-added teacher, is teaching that grade in that school.

　　And you have Mrs. Smith and you end up doing well and scoring high on your tests. Now I come along in 1996, and let's says Mrs. Smith has gone on maternity⁹ leave or is not around for some reason. There is a lot of teacher-switching that we see. Now I don't have the luck to be taught by Mrs. Smith.

　　And so what we find in the data is that such students are—they score lower and then they don't do as well as adults. So the type of variation that I'm describing there is basically random, because the students who happen to get to grade four when a good teacher was there vs. the next year, when a good teacher might not be there, that is essentially¹⁰ random variation. So, those students are comparable, and you are able to control for all those factors that you mentioned.

　　RAY SUAREZ: If we take your study at face value, do its conclusions risk flattening¹¹, simplifying what it is that makes a good teacher, limiting it to achievement on standardized tests?

　　RAJ CHETTY: I think the main message of our study is that standardized test score impacts can be a useful input¹² into evaluating teachers, but by no means are we saying that test scores are the end-all and be-all of how teachers should be evaluated.

　　We think that they're one aspect of what should factor into the formula. One would also want to use things like principal evaluations¹³ or maybe even student evaluations or other measures of teacher quality. But I think there's some useful data here that could be very useful in improving teacher quality.

　　RAY SUAREZ: Unfortunately, Randi Weingarten, of the AFT is stuck in New York City traffic, always an occupational hazard at this time of day.

　　But one thing that teacher unions generally have been keeping an eye on is school systems' attempts to pay for performance, to try to create a formula around their students' achievement that would reward them with cash. After your study, is that justified¹⁴, do you think?

　　RAJ CHETTY: I think teachers who are high-value-added and are raising test scores are having tremendous benefits for their students.

　　So, for example, a teacher who is in the top 5 percent, an excellent teacher, we calculate generates about $250,000 or more of additional earnings¹⁵ for their students over their lives in a single classroom of about 28 students.

　　Now, I think it makes sense to try to reward teachers who are doing extremely well. They're providing a great service to the economy. I think it's important to recognize teachers who are having such great impacts. Whether the best policy to raise teacher value added is merit pay or better teacher training or some other sort of tool is less clear.

　　RAY SUAREZ: You know, a lot of the schools with the worst performance in national standardized tests are also schools in poor neighborhoods, where you also have high teacher turnover¹⁶.

　　If you identify high-value-added teachers, as you call them, how do you get them to stay in a school that needs a lot of help?

　　RAJ CHETTY: That's a great question.

　　High turnover is indeed a problem, because one of the things that we see in the data is that teachers' value-added grows as they become more experienced. So the first time a teacher is teaching, it's quite natural they're learning on the job and they don't do quite as well as after they have a few years of experience.

　　And so in these lower-income neighborhoods, where you have a lot of teacher turnover, that's a further reason that those children are not getting as great opportunities as we think they should be.

　　How you reduce turnover, I think, paying teachers bonuses, especially if they are doing very well, possibly increasing teacher salaries, providing more support so that the classroom environment in which they're teaching is more constructive¹⁷, easier to teach in, I think all of these things could potentially be very helpful.

　　RAY SUAREZ: Is—could it also be concluded from your study that it ought to be easier to fire ineffective teachers? And I'm really sorry the union leader isn't here with us right now when I'm asking this question.

　　But is that part of your conclusion?

　　RAJ CHETTY: Yes.

　　I think—you know, let me make an analogy here. Suppose you are managing a baseball team, say, the Boston Red Sox, and you're trying to do as well as you can. You have players with different batting averages. One approach you might take is to bring the hitting coach out and try to raise the batting averages of the players you have.

　　But I think it also makes a lot of sense—and this will make sense to sports fans—that, on occasion, you might decide to let some of the players with lower batting averages go, and try to get somebody else who might do better. And so I think it makes sense to use a combination of those tools.

　　Here, I think the stakes are even much bigger. We're talking about the future of our children, rather than winning a baseball game. So I think it does make sense to consider those policies seriously.

　　RAY SUAREZ: Professor Chetty, thanks for joining us.

　　RAJ CHETTY: Thank you. My pleasure.

1 gauge   

v.精确计量；估计；n.标准度量；计量器

参考例句：

• Can you gauge what her reaction is likely to be?你能揣测她的反应可能是什么吗？
• It's difficult to gauge one's character.要判断一个人的品格是很困难的。

2 economist   

n.经济学家，经济专家，节俭的人

参考例句：

• He cast a professional economist's eyes on the problem.他以经济学行家的眼光审视这个问题。
• He's an economist who thinks he knows all the answers.他是个经济学家，自以为什么都懂。

3 federation   

n.同盟，联邦，联合，联盟，联合会

参考例句：

• It is a federation of 10 regional unions.它是由十个地方工会结合成的联合会。
• Mr.Putin was inaugurated as the President of the Russian Federation.普京正式就任俄罗斯联邦总统。

4 systematically   

adv.有系统地

参考例句：

• This government has systematically run down public services since it took office.这一屆政府自上台以来系统地削减了公共服务。
• The rainforest is being systematically destroyed.雨林正被系统地毀灭。

5 remarkable   

adj.显著的，异常的，非凡的，值得注意的

参考例句：

• She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
• These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

6 pregnancy   

n.怀孕，怀孕期

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕早期常有恶心的现象。
• Smoking during pregnancy increases the risk of miscarriage.怀孕期吸烟会增加流产的危险。

7 standardized   

adj.标准化的

参考例句：

• We use standardized tests to measure scholastic achievement. 我们用标准化考试来衡量学生的学业成绩。
• The parts of an automobile are standardized. 汽车零件是标准化了的。

8 random   

adj.随机的；任意的；n.偶然的(或随便的)行动

参考例句：

• The list is arranged in a random order.名单排列不分先后。
• On random inspection the meat was found to be bad.经抽查，发现肉变质了。

9 maternity   

n.母性，母道，妇产科病房；adj.孕妇的，母性的

参考例句：

• Women workers are entitled to maternity leave with full pay.女工产假期间工资照发。
• Trainee nurses have to work for some weeks in maternity.受训的护士必须在产科病房工作数周。

10 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

11 flattening   

n. 修平 动词flatten的现在分词

参考例句：

• Flattening of the right atrial border is also seen in constrictive pericarditis. 右心房缘变平亦见于缩窄性心包炎。
• He busied his fingers with flattening the leaves of the book. 他手指忙着抚平书页。

12 input   

n.输入(物)；投入；vt.把(数据等)输入计算机

参考例句：

• I will forever be grateful for his considerable input.我将永远感激他的大量投入。
• All this information had to be input onto the computer.所有这些信息都必须输入计算机。

13 evaluations   

估价( evaluation的名词复数 )； 赋值； 估计价值； [医学]诊断

参考例句：

• In fact, our moral evaluations are merely expressions of our desires. 事实上，我们的道德评价只是我们欲望的表达形式。 来自哲学部分
• Properly speaking, however, these evaluations and insights are not within the concept of official notice. 但准确地讲，这些评估和深远见识并未包括在官方通知概念里。

14 justified   

a.正当的，有理的

参考例句：

• She felt fully justified in asking for her money back. 她认为有充分的理由要求退款。
• The prisoner has certainly justified his claims by his actions. 那个囚犯确实已用自己的行动表明他的要求是正当的。

15 earnings   

n.工资收人；利润，利益，所得

参考例句：

• That old man lives on the earnings of his daughter.那个老人靠他女儿的收入维持生活。
• Last year there was a 20% decrease in his earnings.去年他的收入减少了20%。

16 turnover   

n.人员流动率，人事变动率；营业额，成交量

参考例句：

• The store greatly reduced the prices to make a quick turnover.这家商店实行大减价以迅速周转资金。
• Our turnover actually increased last year.去年我们的营业额竟然增加了。

17 constructive   

adj.建设的，建设性的

参考例句：

• We welcome constructive criticism.我们乐意接受有建设性的批评。
• He is beginning to deal with his anger in a constructive way.他开始用建设性的方法处理自己的怒气。