Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We examine the impact of unions on the quality of educational production by studying a wave of unionization among California charter schools and administrative data on student achievement. We first present new data showing that unions are much more prevalent among charter schools than suggested by previous studies. Using a difference-in-differences identification strategy, we find that unionization increases achievement in mathematics and has no statistically significant impact on English test scores.