When I read the title of the press release – Kindergarten and crime: What’s the link? – immediately causal relation versus correlation came to mind, but the researchers from Duke university argue that they did find a causal link, although I still think that it’s rather a suggestion of a possible causal relation. A strong suggestion via a smart trick, but still a suggestion, with interesting consequences (bold by me).
From the press release:
Children who are older when they start kindergarten do well in the short term, academically and socially. But as teenagers, these old-for-grade students are more likely to drop out and commit serious crimes, says new research from Duke University.
The negative outcomes are significantly more likely for children from disadvantaged backgrounds.
“This research provides the first compelling evidence of a causal link between dropout and crime. It supports the view that crime outcomes should be considered in evaluating school reforms,” said lead author Philip J. Cook, a professor in Duke’s Sanford School of Public Policy.
“Dropouts are greatly over-represented in prison, so we know there is a strong association between dropping out and crime,” Cook said. “But to establish causation requires an experiment. My analysis takes advantage of nature’s experiment associated with birth date.”
The research report, by Cook and Songman Kang of Hanyang University in Seoul, South Korea, is forthcoming in the American Economic Journal-Applied Economics.
The study compared North Carolina public school students born 60 days before and 60 days after the school cutoff date. At the time of the study, North Carolina children had to turn 5 by Oct. 16 to be eligible to enter kindergarten that year.
Previous studies have established that children born just after the school-entry cutoff date, who enter school “old for grade,” perform better academically than their younger classmates. As a result, a growing number of parents have delayed enrolling their children whose birthdays fall shortly before the cutoff date, seeking to gain academic and social advantages. “Academic redshirting” is more common for boys than girls and for whites than African Americans.
In addition to performing better academically, Cook’s study found old-for-grade students were one-third less likely to engage in delinquent behavior while still in school.
“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.”
Among the old-for-grade students, the likelihood of dropping out and being convicted of a serious crime is 3.4 times greater for those born to an unwed mother and 2.7 times greater for those whose mothers were high school dropouts.
“Should you redshirt your kid? Well, on the one hand, he’ll do better while he’s in school and is less likely to become delinquent. On the other hand, he’ll be more likely to drop out before graduation, and bad things may follow that,” Cook said.
Policymakers should take notice, Cook added.
“Even something as crude as a regulation that requires a kid stay in school to a fixed age, whether he wants to or not, has a considerable effect on criminal activity,” Cook said.
Rather than tie legal withdrawal to age, states might consider requiring completion of a certain grade or a specified number of years in school, he said.
“People say there is no point keeping a kid in school who doesn’t want to be there because he won’t learn anything and he’ll be disruptive,” Cook said. “My findings suggest that intuitive argument is not entirely correct.”
“Even students who would rather drop out can benefit from staying in school when they are required to do so. Otherwise they are prime candidates for recruitment into a life of crime,” Cook said.
Abstract of the study (pdf):
Dropouts have high crime rates, but is there a direct causal link? This study, utilizing administrative data for 6 cohorts of public school children in North Carolina, demonstrates that those born just after the cut date for enrolling in public kindergarten are more likely to drop out of high school before graduation and to commit a felony offense by age 19. We present suggestive evidence that dropout mediates criminal involvement. Paradoxically, these late-entry students outperform their grade peers academically while still in school, which helps account for the fact that they are less likely to become juvenile delinquents.