How Much Do Principals Matter When Politicians Choose Them? Evidence from Dated Successions and Close Elections in Brazil

October 2026

Estimates of how much school principals matter differ by an order of magnitude, in part because conventional estimators require principal identifiers and absorb sampling noise into the estimated dispersion. We identify the variance of principal-by-school effects without identifiers, using successions dated by principals' reported tenure in Brazil's 2011 national assessment, which imply known probabilities of a change between consecutive tests. The standard deviation is 0.05 student standard deviations in grade 5 and indistinguishable from zero in grade 9, against 0.18 for plug-in estimates on the same data. Dispersion is concentrated in networks where principals are appointed rather than competitively selected. These estimates imply that principal replacement can explain only a small share of the learning losses that prior work attributes to mayoral party turnover. In close elections, a change in the ruling party replaces municipal principals and, where these posts are discretionary, also disrupts the teaching staff and worsens grade progression. The rules by which principals are chosen matter more than the identity of any individual principal.

Keywords

school principals; principal effects; manager effects; limited mobility bias; patronage; political turnover; bureaucracy; regression discontinuity; teacher turnover; Brazil

Education level

K-12 Education

Topics

Policy, Politics, and Governance