Into the contentious debate over teacher
effectiveness and value-added metrics (VAM) comes this important, timely, and
supersized analysis, conducted by a trio of respected economists with the NBER,
showing that the impact of good teachers follows their students into adulthood.
The analysts pull data from 18 million test scores from roughly 2.5 million
children over two decades (1988 to 2009). They note changes in teaching staff
and find that, when high-value-added teachers (top 5 percent) joined a school,
end-of-year test scores rose immediately in the grade taught by those teachers.
In addition, a one standard deviation (SD) increase in a teacher’s value-added
score raises student achievement by 0.1 SD on average across math and ELA
(which equates to roughly one to two months of learning in a year). The
researchers also meticulously track subsets of students into young adulthood
(using income-tax records, W-2 forms, university-tuition payments,
social-security forms, etc.) and find that the pupils assigned to teachers with
higher value added across all grades are more
likely to attend college, earn higher salaries, live in better neighborhoods,
and save more for retirement. Further, they find with another cohort that, by
age twenty-eight, a 1 SD improvement in teacher value added in a single grade
raises annual earnings by an average of about 1 percent (which could add
roughly $4,600 over a lifetime in additional earnings). And replacing a teacher whose value added is in the
bottom 5 percent with an average teacher in any of the studied grades
(four through eight) would increase the lifetime income of that teacher’s class
by an average of more than $250,000, combined. (That said, the analysts are
unable to control for family connections when they link value-added estimates
to individual earnings, making this particular analysis more of a leap.) Some have questioned whether we can apply these findings,
drawn predominantly from the pre-NCLB era, to today (the argument is that
teachers now may be more apt to teach to the test, and leave out other life
skills that might be important to future success). We can’t know for sure; it
may also be true that the long-term impacts of great teachers could be even larger in
the NCLB era. One thing is for sure, though: This impressive research
does much to advance our knowledge about measuring teacher effectiveness and
the short and long-term impacts of stellar educators.

Raj Chetty, John N. Friedman, and Jonah E.
Rockoff, “The
Long-Term Impacts of Teachers: Teacher Value-Added and Student Outcomes in
” (Cambridge, MA: National Bureau of Economic Research,
December 2011).

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