The following is the executive summary from NIEER's report, The Effects of State Prekindergarten Programs on Young Children's School Readiness in Five States.
"This study estimated the effects of five state-funded preschool programs on entering kindergartners academic skills using a rigorous research design. Receptive vocabulary, early literacy and math skills were assessed in a sample of 5071 children from Michigan, New Jersey, Oklahoma, South Carolina, and West Virginia. We found these state-funded preschool programs to have statistically significant and meaningful impacts on children's early language, literacy and mathematical development, with some evidence of an enhanced program effect for print awareness skills for children in low-income families.
Specific findings are as follows:
- State-funded preschool produces an increase in children's vocabulary scores of nearly 4 raw score points, which equals 31% more growth over the year and an 8 percent increase in children's average vocabulary scores. This improvement translates into an additional four months of progress in vocabulary growth due to the preschool program. This outcome is particularly important because the measure is strongly predictive of general cognitive abilities.
- Children who attended state-funded preschool scored higher on a test of early math skills. State-funded preschool increased children's math scores by almost 1 and a half raw score points, 44% more growth in a year due to the program and a 13 percent increase in children's average math scores. Skills tested include basic number concepts, simple addition and subtraction, telling time and counting money.
- State-funded preschool had strong effects on children's understanding of print concepts. The program increased all children's print awareness scores by nearly 17 percentage points, which is 85% more growth over the year and a 39% increase in children's print awareness scores. Children who attended a state-funded preschool program before entering kindergarten know more letters, more letter-sound associations and are more familiar with words and book concepts.
- We found no significant effects on children's phonological awareness. A relatively new measure was used, and it is difficult to determine whether this result is due to a true lack of program effects. Children in this study appeared to perform well on this test, with or without the preschool program.
Using a sophisticated research design (a regression discontinuity approach) we estimated the gains from one year of state-funded prekindergarten at age 4. Although there were some variations in estimated effects across states (potentially due to differences in populations and availability of other preschool education options), broadly similar effects were found for each of the five state programs. A common element across these programs was that all or nearly all teachers have a four-year college degree with an early childhood specialization."