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 combined lifetime income of that teacher's class by an
average of more than $250,000. (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.)

These findings are incredibly relevant to
Ohio, where state and local education leaders are in the process of developing
teacher evaluation systems that will use value added data to help gauge teacher
effectiveness. 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 the measurements of teacher effectiveness and the short- and
long-term impacts of stellar educators.

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