More than 20 percent of all school-aged children in the United States have vision problems, and low-income and minority children are disproportionately likely to have unmet vision care needs. Vision screening is common in U.S. schools, but it remains an open question whether screening alone is sufficient to improve student outcomes. We implemented…

The sharp regression discontinuity design (RDD) has three key weaknesses compared to the randomized clinical trial (RCT). It has lower statistical power, it is more dependent on statistical modeling assumptions, and its treatment effect estimates are limited to the narrow subpopulation of cases immediately around the cutoff, which is rarely of…