The effect of school entrance age on academic performance

The study investigated the relationships between school achievement and pupil age at entry into first grade and age relative to the class. Data from 101 519 grade 4 pupils were selected from TIMSS 2011 achievement data in mathematics and science, collected from national samples of 25 European countries. Hierarchical regression analysis showed that the effect of class relative age was greater than the effect of grade relative age and it was significantly higher in younger than older classes. Average achievement (especially in science) was better in older classes.

http://www.edukacja.ibe.edu.pl/images/numery/2014/5-1-konarzewski-effect-of-school-entrance.pdf