International differences in teacher quality are commonly hypothesized to be a key determinant of the large … data, we construct country-level measures of teacher cognitive skills. We find substantial differences in teacher cognitive …-effects estimation exploiting within-country between-subject variation in teacher skills. Observed country variations in teacher …

Teachers differ greatly in how much they teach their students, but little is known about which teacher attributes … account for this. We estimate the causal effect of teacher subject knowledge on student achievement using within-teacher … subjects. We circumvent omitted-variable and selection biases using student and teacher fixed effects and observing teachers …