The study is known as the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development. It is said to be the largest, longest lasting and most complete study of child care in the United States.

BOB DOUGHTY: The children included in the study were born around nineteen ninety-one in ten areas of the country. Researchers examined the quality and amount of child care the children received until they were four and one-half years old. Child care included any care provided by people other than the child’s mother that lasted at least ten hours a week. This included any care given by fathers or other family members.

The researchers then examined each child’s performance in school and social development. They also measured other influences, such as the quality of classroom education and parenting.

FAITH LAPIDUS: The researchers examined whether the developmental qualities that had been observed in young children were still present a few years later. They found that the older children who had received higher quality child care continued to show better ability in tests of language skills.

Researchers tested the children’s ability to name objects shown in a series of pictures. The study confirmed that a link between high quality child care and better test results continued as the children grew older. It also found that the children’s ability was not dependent on the amount of time they had spent in child care.