Calendar effects and education, ACT/SAT, etc

[LostInTheShuffle]

@MWDadOf3

Studying this question would be confused by a few issues:

• Different states have different date cutoffs for kindergarten, and some may be harder/softer
• Sometimes, delayed entry into Kindergarten is correlated with immaturity (two kids with same B-Day - the less mature one gets held back by his parents)
• Of course, kids can also get held back during K-12, and such kids are likely those who struggle academically.

I’d add to this list differences in “intrinsic capabilities” because humans are not equal in this regard (such that physical age becomes the key determinant of outcomes). But maybe that’s implied in your third bullet.