Does one plus one always equal two? Examining complementarities in educational interventions
研究社区层面的干预（如延长在校时间）如何增强个体层面政策（如留级政策）的效果，发现对资源匮乏的学校，两者结合能显著提升留级政策的有效性，缩小与资源较好学校的差距。
Abstract Public policies targeting individuals based on need often impose disproportionate burden on communities that lack the resources to implement these policies effectively. In an elementary school setting, I examine whether community‐level interventions focusing on similar needs and providing resources to build capacity in these communities could improve outcomes by improving the effectiveness of individual‐level interventions. I find that the extended school day policy that targets lowest‐performing schools in reading in Florida significantly improved the effectiveness of the third‐grade retention policy in these schools. These complementarities were large enough to close the gap in retention effects between targeted and higher‐performing schools.