"The benefits of being younger are even greater for those who skip a grade, an option available to many high-achieving children. Compared with nonskippers of similar talent and motivation, these youngsters pursue advanced degrees and enter professional school more often."
Well, technically they are saying that they compared the skippers to similar non-skippers so the effect should be from the skipping itself.
HOWEVER, I question their ability to really do this in the study. How did they measure the similarity in talent? If they just took the top 3-5% of a grade level achievement test score, for example, we have no way of knowing if the two groups are "similarly talented" because any variation between very bright, gifted, HG, PG, etc. is hidden.
I do appreciate the argument about how important it is to teach kids at a challenging level, however.
Also, they don't address the issue of preschool in the article. While the kindergarten age has gone up, kids are much more likely to attend preschool than they were a few decades ago. So kids are not necessarily getting less schooling. Also, kinder is much more likely to be full day now. So, you could argue that preschool is replacing the old half day kinder and kinder is being added as a new "grade". So in fact, kids are getting MORE schooling than in previous years. That said, I would think that NOT going to preschool would be a disadvantage today possibly.
