Seattle Preschool Program RCT
University of Washington / City of Seattle · Seattle, WA, USA · 2017
Summary
Seattle's Preschool Program produced one of the few lottery-based RCTs of a universal municipal pre-K program in the United States. The lottery-based design — created by program oversubscription, not by deliberate randomization — provided a credible control group. Effects of roughly one-third of a standard deviation in school readiness are consistent with other high-quality early childhood programs and substantially larger than typical short-term education interventions. The finding that effects were largest for dual-language learners and the lowest-income children supports the targeting argument: universal programs can deliver their largest benefits to the most disadvantaged participants when quality is maintained.
Research question
"Does a universal publicly funded preschool program improve kindergarten readiness for low-income children?"
Methodology
Intervention
Lottery-allocated access to Seattle Preschool Program seats for 3- and 4-year-olds; program provided full-day structured preschool with teacher quality standards and family support services
Assignment
Lottery-based randomized controlled trial (oversubscribed program)
Sample size
280 children (140 lottery winners, 140 wait-list controls)
Primary outcome
School readiness composite (cognitive, language, social-emotional); kindergarten assessment scores
Effect estimate
School readiness: +0.32 SD; language development: +0.28 SD; social-emotional skills: +0.19 SD; effects largest for dual-language learners and lower-income families
Decision
City expanded SPP enrollment; results used to support Washington State universal pre-K legislation; follow-up study at 3rd grade in progress
Result
Positive
School readiness: +0.32 SD; language development: +0.28 SD; social-emotional skills: +0.19 SD; effects largest for dual-language learners and lower-income families
Evidence strength
Strong
Randomized controlled trial with large sample.
Replication status
Partially replicated
Institution
University of Washington / City of Seattle
Location
Seattle, WA, USA
Year
2017
Policy area
Early Childhood
Mechanism
Human capital