Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
The effects of class size on scholastic achievement are estimated using a seasonal feature of the school system. The fact that schools are in session during the school year and out of session during the summer makes it possible to control for non‐school influences on both the level of and changes in achievement. Using Swedish data, smaller classes are found to generate higher test scores and this effect is larger for immigrants. The results are also compared with those from applying the same data to the widely used value‐added model.