Or, were those who were held back those who suffered even a year later from not being well suited for the sit and drill classroom?
This has been looked at in a large study. At age 4, kids who would later be redshirted (not known at the time) were assessed and deemed just as academically and socially ready for K as any other child.
I will say that I scanned one of the studies linked in this NYer piece, based on what a commenter said, and the article is misleading. Yes, Swedish adults who entered late earned less eventually--but not due to being poorly educated or having worse jobs. It was just the result of having one less year in the workforce. Big deal.
