They argue that this is the case if the unobserved center quality characteristics are correlated with other independent variables
4) The NAEYC accreditation criteria include guidelines for staff-child interaction, curriculum content, staff qualifications and training, group size and adult-child ratios, physical environment and safety, nutrition.
5) The other variables included in the model are average hourly wages for teachers and aids; rent; cost of other supplies and services per child; indicators for whether a center is for-profit, serves infants, serves children with disabilities, has operated for less than two years; and geographic location.
7) The authors do control for centers that provide infant care, but cost structures would nevertheless be expected to differ, for example, in infant-care centers that do not provide care to 4- and 5-year-olds.
8) The relationship between structural measures of quality and total variable costs are also tested, but there is no evidence of statistically significant relationships. The authors note that their index measure of quality may be a theoretically superior measure insofar as the structural characteristics capture only a portion of the “true” measure of quality.
