"Up until the 16th birthday, it is all positive," Cook said. "They are doing better, relative to their classmates, by every measure. It makes sense, because they are more mature."
But after age 16, the picture shifts, Cook's research shows. The old-for-grade students are more likely to drop out and be convicted of a felony before age 20. The explanation for the seeming contradiction lies in the age at which students may legally withdraw from school, which is 16 in North Carolina.
"If they were born before the cutoff date, they have just 19 months between their 16th birthday and graduation to be tempted to drop out," Cook said. "If they were born just after and enter school later, they have 31 months, and for some of them, it is an irresistible temptation."
"It's human nature," Cook said. "For a lot of adolescents, high school is a drag."
I can't imagine this is much of an issue for middle class students with involved parents. I have no dog in this fight. My kid is a November birthday and will be in school on time.