UC Irvine

Current challenges in child development science and education policy include the nature of heterogeneity in early childhood education (ECE) programs’ long-term impacts and their related explanatory mechanisms. Building on theories of skill-building and institutional gateways, the present dissertation addresses some of these challenges. More specifically, I investigated impacts’ variations relative to changes in counterfactual conditions, replicating and extending on a previous ECE program’s evaluation. Then, I tested the hypotheses that factors producing general gains yield impacts that persist, whereas factors producing specific gains yield impacts that fade. I did so by examining the properties of an ECE intervention’s impact on a broad range of cognitive skills. Finally, I attempted to explore some of the patterns underlying the “dark matter” mediating the long-run impacts of ECE interventions by analyzing patterns in the patterns of indirect effects of two ECE programs on educational attainment. In the first study, I replicated Deming’s Head Start study (2009), and appended 10 additional years of data. Using a sibling-comparison design, I replicated positive long-term impacts of Head Start observed in a previous analysis but found no statistically significant impacts on earnings and mixed evidence of impacts on other outcomes when estimated later into adulthood. I repeated the analysis with later cohorts, born to older mothers, and find mostly null and sometimes negative impacts. Finally, combining all cohorts showed generally null impacts on school-age and early adulthood outcomes. I found suggestive evidence that the heterogeneity of Head Start impacts across cohorts was due largely to changes in counterfactual conditions of household characteristics within the sample, notably mother’s age at child’s birth. In the second study, I probed the hypothesis that persistence is unlikely when gains are specific to trained skills and distinguishable from impacts on general cognitive ability. I re-analyzed data from the randomized Abecedarian intervention to probe whether its persistent impact on cognitive skills was linked to impact on cognitive subtests shared variance (i.e., on psychometric g factor). Conducting various measurement invariance tests, I found that impacts were broadly distributed and not distinguishable from impacts on psychometric g. Additionally, I estimated that a subtest-specific impact not-well captured by psychometric g faded. These findings supported the raising IQ/raising g distinction hypothesis, which posits that impacts on cognitive skills are more likely to persist if they generalize across psychometric tests than if they can only be detected on a subset of tests. Breadth of impact might be a worthwhile theoretical and practical proposition in the study and design of ECE interventions with persistent impacts. The final study considered mechanisms translating ECE programs’ initial impacts into longer-term effects. Proposed explanatory pathways leave much of the total impact on long-term outcomes unexplained (so-called ECE intervention “dark matter”). Unidentified mediators are more likely to be proximal if closely aligned with intervention’s features, and more likely to be distal if measuring processes like skill-building or institutional gateways. Thus, leveraging panel data, I considered a series of mediators, grouped as a set across various time-points. Inferences were made about unexplained effects of the “dark matter” from patterns of indirect effects via these observed mediators bundles. Indirect effects were relatively stable, accounting for up to 50 and 20 percent of the impact on educational attainment from Abecedarian and Head Start, respectively. By implication, effects from the “dark matter” were also relatively stable. These findings were consistent with the hypotheses that earlier skills contributed to later institutional gateway process; and that pathways, possibly coupling environmental dimensions with behavior, ran parallel to our chosen mediating bundles and ought to be specified. The final chapter concludes with discussing some of the implications raised by the three studies. I also proposes two lines of research aiming to further address ECE-interventions’ efficiency and long-run impact mechanisms through the life-cycle.