Scott Alexander admits he was wrong about preschool programs like Head Start, discussing new evidence of their long-term benefits and considering the implications for understanding environmental effects and policy. Longer summary

Scott Alexander reflects on his previous skepticism about the effectiveness of preschool programs like Head Start, admitting he was wrong based on new evidence. The post discusses research showing that while preschool doesn't improve academic skills or IQ, it does lead to better long-term life outcomes such as staying in school longer, getting better jobs, and committing less crime. Scott speculates that these benefits might stem from social factors like freeing up parents' time or exposing children to different environments. He also grapples with how this conflicts with studies showing little impact of shared environment on outcomes, and considers implications for policy support of universal childcare or pre-K programs. Shorter summary