Examining Environmental Heterogeneity in the Long-Term Effects of NC Pre-K

• In Event: Disentangling Heterogeneity in the Impact of North Carolina’s Public Pre-Kindergarten Program

Abstract

Mixed evidence of the long-term effects of pre-kindergarten programs has led to several recent reviews attempting to provide theoretical explanations for the divergent findings across contexts, most of which rest on the premise that the effects of pre-k exposure vary systematically as a function of other environmental factors (e.g., Abenavoli, 2019; Bailey, Duncan, et al., 2020; Bailey et al., 2017). Using data from North Carolina’s pre-kindergarten program (NC Pre-K), which has shown positive effects on students’ academic test scores through fifth grade, we examine environmental factors that are measured before, during, or after the pre-k year and might explain heterogeneity in the observed long-term effects.

We test three hypotheses to explain environmental heterogeneity. First, effects would be complementary if the positive effect of NC Pre-K are further enhanced by the positive effect of an environmental factor (i.e., a positive interaction). Second, we would see compensatory effects if the effect of exposure to pre-k compensates for the ill effects of an adverse environmental experience (i.e., a negative interaction). Third, additive effects would be observed if two experiences exert independent effects on child outcomes, but they do not interact in any meaningful way (i.e., no significant interaction).

Our sample, described in detail in the panel statement, includes population level data on children attending public schools in NC. Using a difference-in-differences analytic approach that exploits year-to-year variation in NC Pre-K funding at the county level, we test interaction effects between levels of NC Pre-K funding and a host of moderating factors measured across development from birth through fifth grade, including access to other early childhood education experiences, the quality of the subsequent elementary school environment, and economic characteristics of the child’s community (listed in Table 1).

Our findings are summarized in Table 1. Across most tested moderators, we found evidence for additive effects, where moderators produced significant main effects on student achievement outcomes but non-significant interactions with NC Pre-K funding. However, we also found evidence to support a compensatory effect for four moderator variables: NC Pre-K funding protected children from adverse effects of low school achievement, low school-level federal funding, lower levels of teacher experience, and higher rate of SNAP benefits in the county (that is, larger effects of NC Pre-K were observed under adverse conditions). Findings were generally similar for math and reading achievement, though effects were larger for math in several cases.

Contrary to recent expectations in the field regarding dynamic complementarity and sustaining environments, we found little indication that the benefits of NC Pre-K were enhanced in the presence of other high-quality environmental exposures after preschool. Yet our finding that pre-k may serve as a protective factor that buffers students from future negative circumstances is novel, and provides a new direction for research examining the conditions under which pre-k is most effective.

Authors

• Maria Sauval, University of California - Irvine
  Presenting Author

• Tyler Watts, Teachers College, Columbia University

• Jade V Marcus Jenkins, University of California - Irvine

• Kenneth A Dodge, Duke University

• Robert C. Carr, University of North Carolina at Chapel Hill