The impact of teacher skills on student performance across countries

Student performance differs greatly across countries, but little is known about the role of teacher quality in explaining these differences. New international data from the PIAAC survey of adult skills allow for the first time to quantify teacher skills in numeracy and literacy, providing country-level measures of teacher subject knowledge. Our student-level regressions with PISA data exploit between-subject variation to overcome bias from unobserved country heterogeneity and control for parent skills to account for the persistence of skills across generations. We find that a one-standard-deviation increase in subject-specific teacher skills raises student performance by 7 percent of a standard deviation in math and 6 percent in reading.