An alternative research strategy has been to consider aggregated structural and caregiver characteristics. For example, the NICHD Study of Early Child Care (NICHD Early Child Care Research Network, 1999a) assessed four structural and caregiver characteristics (child:staff ratio, group size, caregiver specialized training in child development or early childhood education, and caregiver formal education) in terms of guidelines recommended by the American Public Health Association. The investigators then summed the number of structural and caregiver characteristics that met recommended guidelines, resulting in summed scores of 0 to 4. At 24 months, 10–12 percent of classrooms met all four standards, whereas 34 percent of the classrooms did so at 36 months. At 24 months, 9 percent of the observed centers met none of the recommended standards; 3 percent of the centers met none of the standards at 36 months.
Associations between the number of child care standards that were met and child outcomes were then tested, with family income and maternal sensitivity controlled (see Table 4). Children who attended centers that met more recommended guidelines had fewer behavior problems at 24 and 36 months, and higher school readiness and language comprehension scores at 36 months. There were significant linear trends between the number of recommended standards that were met and children’s concurrent adjustment.
Analyses also compared children who were enrolled in classrooms that met a given individual standard with children whose classrooms did not meet that standard (see Table 4).