Referenced by President Obama in his 2012 State of the Union Address, this study has been cited in high-level debates about how to improve the US’s education system. This study showed for the first time the enormous impact great teachers have on their students. Their influence goes far beyond the classroom, and thereby they strengthen both the American society and economy. Graduates that had good teachers have, among others, less teenage pregnancies and live in better neighborhoods.
Value added approach
Previous debates on assessing teacher quality have centered on the validity of what is commonly termed the “value-added” (VA) approach. In this approach, a teacher is rated based on the average test score gain for his students, adjusted for differences across classrooms. Researchers Raj Chetty and John Friedman of Harvard and Jonah Rockoff of Columbia examined two questions:
- Does the VA method accurately measured teachers’ impacts on student scores
- Do teachers with high VA scores actually improved their students’ long-term outcomes, as opposed to being merely better at teaching to the test?
Increased life earning
The study tracked over 1 million students from a large urban school district from fourth grade into adulthood. This showed that having a good teacher has a powerful effect on many of a student’s life outcomes. The effects extended far beyond graduation, decades into the future lives of the students. The report showed that replacing a poor teacher with, not even an excellent, but an average teacher will increase a student’s life earning with $52,000. The effect of a good teacher on long-term earnings is so dramatic that the authors calculate that parents should be willing to pay roughly 25 percent of what they expect their child’s income to be at age 28 to be to switch their child from a below-average (25th percentile) to an above-average (75th percentile) teacher.