There have been dozens of studies over the years about the best age for a child to start kindergarten.

New York state will not be adding to the mountain of literature on the subject.

Gov. Andrew Cuomo has vetoed legislation passed at the end of the state legislative session in June studying the feasibility of adjusting the age when children must start school in New York state. A.7559A, sponsored by Assemblywoman Patricia Fahy, D-Albany, wanted the state Education Department to finish the study by July 1, 2021. The legislation passed the state Assembly, 143-1, with only Assemblyman Mark Walczyk, R-Watertown, voting against the bill.

Fahy wrote in her legislative justification that children who are 4-years-old when they begin kindergarten are often too young developmentally for kindergarten and struggle academically. In New York state, children aren’t required to begin kindergarten until they are 6 years old, as long as they turn 6 before Dec. 1.

“Though New York State law states that children must begin school by age six, most school districts provide a kindergarten program to five year olds or children about to turn five,” Fahy wrote. “Many children who turn five after Sept. 11 are not as ready for school developmentally, as compared to children who turn five before Sept. 1 and, as a result, suffer long term educational challenges. Studying the ability of the state to shift the age requirements will help state education officials anticipate the needs and challenges of bringing start ages in line with our present understanding of educational development.”

A 2015 study, “School Starting Age And Mental Health,” published by the National Bureau of Economic Research stated children may not be ready for kindergarten until they are 6 years old, with the study of tens of thousands of children in Denmark showing a four-year decrease in inattention and hyperactivity.

At the time of the study, the percentage of children entering kindergarten at age six instead of age five had steadily increased to about 20 percent in the United States.

“It’s not just a question of when do you start kindergarten, but what do you do in those kindergarten classes?” said Thomas Dee, Stanford Graduate School of Education professor in 2015. “If you make kindergarten the new first grade, then parents may sensibly decide to delay entry. If kindergarten is not the new first grade, then parents may not delay children’s entries as much.”

A 2008 working paper by Harvard economist David Deming and public policy expert Susan Dynarski of the University of Michigan showed students who delayed kindergarten were more likely to drop out of school and tended to earn less and score lower on IQ tests as adults. Deming and Dynarski also point out that simply delaying kindergarten by a year doesn’t take into account how much a child is learning — or not learning — at home in place of time in kindergarten. Delaying school for a year could intensify the achievement gap between low-income and upper-income children.

“First, increases in the age of legal school entry intensify socioeconomic differences in educational attainment,” the study states. “Lower-income children are at greater risk of dropping out of school when they reach the legal age of school exit; increases in age at school entry therefore disproportionately decrease their completed education. Further, young children who enter school later spend more time in unequal environments. Whether at home or in formal care, children who start school later linger in settings whose quality is positively correlated with parents’ human capital. This point is exactly the one made by advocates of early childhood interventions: insofar as home environments are unequal, delaying public schooling increases the likelihood of unequal outcomes.'”