Teachers impact students’ future earnings

(Last of three parts)

Good teachers motivate students. Great teachers inspire.  But do good teachers also help their students in a practical way?

Do teachers affect students’ future earnings?

Yes, they do. In two papers for the United States National Bureau of Economic Research, economists Raj Chetty and John Friedman of Harvard University and Jonah Rockoff of Columbia University reviewed two decades’ worth of data involving more than a million students in an urban school district.

They looked at many factors, from parents’ tax records to teachers’ performance within and among schools.

Last week, we learned that good teachers did have a positive influence on student academic achievement. Now let us look at teacher influence on students’ future earnings.

Higher lifetime income

The researchers find: “A 1 standard deviation improvement in teacher VA (value-added) in a single grade raises the probability of college attendance at age 20 by 0.82 percentage points, relative to a sample mean of 37 percent. Improvements in teacher quality also raise the quality of the colleges that students attend, as measured by the average earnings of previous graduates of that college.”

VA refers to how much

improvements teachers can make on student national achievement test grades.

There’s more. “Students who are assigned higher VA teachers have steeper earnings trajectories in their 20s. At age 28, a 1 standard deviation increase in teacher quality in a single grade raises annual earnings by 1.3 percent.”

Influences add up. “If the impact on earnings remains constant at 1.3 percent over the lifecycle, students would gain approximately $39,000 on average in cumulative lifetime income from a 1 standard deviation improvement in teacher VA in a single grade.”

What about the effects of poor teachers? The researchers are pragmatic.

Students do not need the best teachers to improve; they will benefit even from average ones.

“Replacing a teacher … in the bottom 5 percent with an average teacher would increase the present value of students’ lifetime income by approximately $250,000 per classroom.”

Math and English

Teacher influence is not equal, across the board. English and mathematics are basic subjects in all schools. Is there a difference in teacher influence between the two fields?

I am a professor of math and psychology, but I was once awarded a professorial chair to handle a creative writing class in English, an experience I thoroughly enjoyed. None of my students were science majors, but I required them to write (among other things) a high-quality science paper.

With class critiques and lots of guidance, the students produced exceedingly good papers, some of which won the Ateneo de Manila School of Science Dean’s Awards for Creative Science Writing.

One of the papers, after revisions, even won a Palanca Award for Essay.

Having taught English once, I was intrigued to discover that, according to the economists’ studies, English teachers have a bigger influence than math mentors on students’ future college performance.

“One standard deviation increase in teacher VA in English has larger impacts on college quality than … in teacher VA in math,” say the researchers.  “An English teacher who raises her students’ test scores by 1 standard deviation raises college quality by 2.3 times as much as a math teacher who generates a commensurate test score gain.  Hence, the returns to better performance in English are especially large, although it is much harder for teachers to improve students’ achievement in English.”

The researchers did not speculate on why it was harder for teachers to influence students in English rather than in math (I personally think there should be no difference).

But, if we assume that the researchers are right, then the conclusion is clear.

“Even though teachers have much smaller impacts on English test scores than math test scores, the small improvements that good teachers generate in English are associated with substantial long-term impacts.”

Good elementary English teachers can and do influence students, not just by instilling a love of reading or literature, but in ways, economic and otherwise, they may not realize.

Improve teacher quality

According to the researchers, two main methods are practiced in the US to improve teacher quality. The first is to replace weak teachers. The second is to pay good teachers more so they will stay. Which is better in the long run?

Judging by the data, the researchers say, “Replacing ineffective teachers is more cost-

effective than attempting to retain high VA teachers.”

Researchers say making teacher salaries high enough, to start with, makes the profession more attractive to better qualified individuals, which may generate a win-win cycle for everyone.

I tend to agree with the researchers’ conclusions, though I would likely give weak teachers a chance to improve, such as by training them. But given what we now know, that poor teachers do not just affect student motivation or performance, but even student earnings, if weak teachers do not want to improve themselves, then they should just leave the profession.

The researchers believe that parents also play a significant role. Instead of complaining about tuition fees, parents should help the school retain good teachers.

“Consider a teacher whose true VA is 1 standard deviation above the mean [but] who is contemplating leaving a school. Each child would gain approximately $39,000 in total (undiscounted) lifetime earnings from having this teacher instead of the median teacher. With an annual discount rate of 5 percent, the parents of a classroom of average size should be willing to pool resources and pay this teacher approximately $200,000 ($7,000 per parent) to stay and teach their children during the next school year.”

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