Health and income are strongly correlated both within and across countries, yet the extent to which improvements in income have a causal effect on health status remains controversial. We investigate whether short-term fluctuations in aggregate income affect infant mortality using an unusually large data set of 1.7 million births in 59 developing countries. We show a large, negative association between per capita GDP and infant mortality. Female infant mortality is more sensitive than male infant mortality to negative economic shocks, suggesting that policies that protect the health status of female infants may be especially important during economic downturns.

We study the impact of classroom rank on children’s learning using a unique experiment from Ecuador. Within each school, students were randomly assigned to classrooms in every grade between kindergarten and sixth grade. Students with the same ability can have different classroom ranks because of the (random) peer composition of their classroom. Children with higher beginning-of-grade classroom rank have significantly higher test scores at the end of that grade. The impact of classroom rank is larger for younger children and grows over time. Higher classroom rank also improves executive function, child happiness, and teacher perceptions of student ability.

We assigned two cohorts of kindergarten students, totaling more than 24,000 children, to teachers within schools with a rule that is as good as random. We collected data on children at the beginning of the school year and applied 12 tests of math, language, and executive function (EF) at the end of the year. All teachers were filmed teaching for a full day, and the videos were coded using the Classroom Assessment Scoring System (or CLASS). We find substantial classroom effects: A 1 standard deviation increase in classroom quality results in 0.11, 0.11, and 0.07 standard deviation higher test scores in language, math, and EF, respectively. Teacher behaviors, as measured by the CLASS, are associated with higher test scores. Parents recognize better teachers, but do not change their behaviors appreciably to take account of differences in teacher quality.