Association for Public Policy Analysis & Management

As the only large-scale randomized experiment in Head Start history, the Head Start Impact Study (HSIS) reported short-term benefits of Head Start after one-year participation, while few benefits were maintained in kindergarten, first grade, or third grade. Children in the HSIS control group were placed a mixture of alternative care settings. An analysis of HSIS data through first grade has shown that the effects of Head Start varied substantially contingent on the alternative child care arrangements. For example, compared to children in parental care and relative/non-relative care, Head Start participants generally had better cognitive and parent-reported behavioral development, with some benefits of Head Start persisting through first grade; while few differences were found between Head Start and other center-based care.

In this study, we use the HSIS data through third grade to further examine the effects of Head Start on children's growth trajectories compared to alternative child care arrangements, including parental care, relative/non-relative care, another Head Start program, or other center-based care. The analysis sample includes 3,790 children (2,119 in the 3-year-old cohort and 1,671 in the 4-year-old cohort) from 353 Head Start centers in the HSIS. We focus on the repeated measures of children’s academic and social-behavioral outcomes collected in preschool, kindergarten, first grade, and third grade. Children's academic outcomes were collected from direct assessment, including the Peabody Picture Vocabulary Test (PPVT) Receptive Vocabulary and the Woodcock-Johnson III subscales of Letter-Word Identification and math in Applied Problems. Information on social-behavioral development was reported by parents, including Social Skills and Positive Approaches to Learning, Aggressive Behavior, and Hyperactive Behavior.

There is an issue of self-selection because children in the control group chose different care arrangements due to variation in pretreatment covariates. Similarly, children in the treatment group would also have chosen different arrangements if they had been assigned to the control group. To address this issue, we use a principal score approach to identify subgroups of children in the treatment group who, without the intervention, would have had child care arrangements similar to subgroups of children in the control group. Children with similar principal scores are then are compared using matching and weighting strategies. To examine whether Head Start had beneficial effects on children’s growth trajectories compared to specific child care arrangements in the control group, we conduct growth curve models to specify linear growth rates as well as nonlinear changing growth (i.e., acceleration or deceleration) rates over time.

The analysis of the HSIS data through first grade suggests that Head Start participants had lower growth rates in academic outcomes than children in parental care or relative/non-relative care and lower declining rates in hyperactive behavior than children in parental care. Further analyses will be conducted to include the HSIS third grade data. The findings of this study may provide important implications regarding the children for whom Head Start is most beneficial as well as how well Head Start compares to other center-based programs.