I also live in Quebec and I've been told by people that the education system (meaning primary and secondary education) has changed quite a bit, not for the best

I also live in Quebec and I've been told by people that the education system (meaning primary and secondary education) has changed quite a bit, not for the best, since 1997. In addition, one of the measures in the study is hyperactivity and anxiety in school age children, and what I've heard relative to that is there are more diagnoses because before children were not being detected that young. I would have liked the study to try harder at controlling the effect, for example by comparing cohorts in regions where use of the government funded childcare is more/less common. Quebec has plenty of remote regions where people are more likely to rely on extended family for care. The comparison group for the crime rate effect is the rest of Canada -- what the data essentially says is, at the time of data collection, you were more likely to be a criminal as a Quebec teen vs a teen in the rest of Canada if you were born in 1998-2000, instead of 1993. The authors interpret this as "exposure to child care", but the more appropriate meaning is probably that younger teens are more likely to commit crimes in Quebec. It would be difficult to see why -- except there are also more high school dropouts in Quebec and the school system means 17 year olds are a lot more likely to have the kind of freedom that lets one commit crimes in Quebec. IDK, on this one, I buy the correlation but not the causation. (They break up crime by type and they're not overwhelmingly drug crimes though. So whichever is the cause for this effect, it's not solely drug related.)