A 23-year Harvard and Columbia University study was recently published shedding new light on the long-term impacts of teachers with both high and low value-added estimates. Researchers Chetty, Friedman, and Rockoff tracked math and reading assessment data on over 2.5 million students from 1989-2009. They then incorporated 90% of these students’ tax records from 1996-2010 to analyze the long-term outcomes highlighted below. For anyone interested in the return on investment for a high value-added (VA) teacher, you now have it expressed in student outcomes and life opportunities:
|“Being assigned to a higher VA teacher in a single grade raises a student’s probability of attending college significantly,” through age 25. At age 20, it is relative to a mean of 37.8%. (pg. 36-37 of the report) Additionally, “there is a highly significant relationship between the quality of colleges students attend and the quality of teachers they had in grades 4-8.”|
|“Being assigned to a higher value-added teacher has a clear, statistically significant impact on earnings.” (Pg. 39) Replacing a poor teacher with an average one would raise a single classroom’s lifetime earnings by about $267,000, the economists estimate. (pg. 48) Additionally, “increases in teacher VA raise earnings even in subgroups that are relatively unlikely to attend college, suggesting that better teaching has direct returns in the labor market independent of its effects on college attendance.” (pg. 40)|
|Having a 1 SD increase in teacher VA raises neighborhood quality by 0.063 percentage points (0.5% of the mean), measured by the percent of college graduates living in that neighborhood. “The impact on neighborhood quality more than doubles at age 28, consistent with the growing earning impacts documented above.” (pg. 42)|
|Having a 1 SD higher VA teacher in a single year from grades 4-8 reduces the probability of a teen birth by roughly 1.25%. (pg. 41)|
|Mixed results were consistent with the college attendance and earnings findings: “In schools with low college attendance rates, students who have high VA teachers, find better jobs by age 25 and are more likely to start saving in 401(k)’s. In schools with high college attendance rates, students with high VA teachers are more likely to be in college at age 25 and thus may not obtain a job in which they begin saving for retirement until they are older.” (pg. 42)|
Critics of value-added analysis say that it places too much focus on standardized testing, since assessment data is used as an input for the models. A concern is that this will motivate “teaching to the test” and lead to a narrowing of the curriculum.
First, we need to define what “teaching to the test” really means. If it means teaching to all of the standards and objectives in the curriculum, which reflect what we want students to learn in preparation for a final exam that measures their proficiency and readiness to move on to the next academic level, then in my book that is simply called “teaching.” If it means a majority of instructional time is spent on “drill and kill” review sessions for the final exam, then that is cause for concern due to the reduction of engagement, inquiry-based, or project-based learning.
Second, this argument highlights a misconception of the way value-added analysis works. In reality, while teaching to the test might have a positive impact on student achievement, it might actually have a negative impact on value-added estimates, which measure progress. (See my October blog to better understand the difference between measuring achievement and progress.)
In value-added analysis, all students count, regardless of their achievement level. By teaching a narrowed curriculum, very low achieving as well as very high achieving students will have limited opportunities to make appropriate academic growth. In essence, the teacher or school is less likely to be highly effective from a value-added perspective.
The above mentioned research study gives me the feeling that the high value-added teachers did much more than “teach to the test” to yield the magnitude of positive outcomes described. You don’t reduce teenage pregnancy while increasing college attendance, earnings, and retirement savings with your students by merely “drilling and killing” with test review. Those teachers most likely engaged their students to create inquisitive lifelong learners, and incorporated college and career exploration into their discussions and assignments.
I think that a great follow-up study would be to interview those high VA teachers to find common instructional practices that contributed to their success. In the meantime, at least we have some empirical evidence showing the importance of measuring teaching effectiveness with value-added analysis. It can help all teachers improve and contribute to similar outcomes and opportunities for their students.