A new article in Educational Evaluation and Policy Analysis presents findings from a large-scale, lottery-based study of charter schools (US schools that are publicly funded, but operate outside the established state school system), and results are mixed.
The study involved 33 charter middle schools in 13 states. These schools had a larger number of applicants than spaces available, so they relied on admissions lotteries to admit students. For the present study, students who won the lottery and were offered admission to study schools formed the treatment group, while those who did not win the lottery formed the control group. The full study sample included 2,904 students: 1,744 in the treatment group and 1,160 in the control group.
To measure the effects of the charter schools on student achievement, researchers examined test score data from state assessments. These data were obtained from schools, districts, or states for the baseline year and the preceding “pre-baseline year”, as well as for two follow-up years.
The researchers found that impacts varied considerably across schools and students, with more positive impacts for more disadvantaged schools and students, and more negative impacts for the more advantaged. However, on average, the charter schools in the study had non-significant negative impacts on student achievement in reading and maths.
The researchers caution that there are limitations to the study. For example, the schools were not randomly selected for the study, and the study focuses on charter middle schools and does not produce evidence on the effects of charter schools at the elementary or high school levels.
Source: Do Charter Schools Improve Student Achievement? (2016), Educational Evaluation and Policy Analysis.