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Charter School Achievement: What We Know
Prepared by Bryan C. Hassel, Public Impact


Several recent reports have raised questions about the performance of public charter schools. To answer these questions, and provide a full and fair picture of how charter schools are actually doing, the Charter School Leadership Council commissioned an extensive review of the available research on charter school achievement.

The following report summarizes and evaluates 38 comparative analyses of charter school and traditional public school performance, including a study-by-study look at central findings and methodological strengths and weaknesses. All of these studies fell into one of two categories: 1) snapshot pictures of one or more points in time; or 2) longer-term measures of change over time. In addition, all met four criteria for rigor and relevance: they are recent (2000 or later), compare charter vs. traditional public school performance, use serious (though often flawed) analytical methods, and examine a significant segment of the charter sector. The key findings are:

STUDY QUALITY: The quality of available research varies widely.
The stronger studies typically offer information about how much value charter schools are contributing to their students; study an adequate number of students and schools to be meaningful; use sound comparisons when assessing relative performance of traditional public schools vs. charters; and "disaggregate" analysis to show how well different kinds of students and schools are doing. Many studies fall short on one or more of these standards.

SNAPSHOTS: The results are mixed and of limited use.
Of the 38 studies, 17 look only at a snapshot of performance at one or more points in time. Nine show charter schools generally underperforming traditional public schools. The other eight show comparable, mixed, or positive results for charter schools. These studies, however, fail to examine the progress students and schools make over time, so they are of limited use in drawing conclusions about the effectiveness of charter schools.

CHANGE-OVER-TIME: The results, while far from conclusive, are encouraging.
The other 21 studies look at change in performance over time. Nine follow individual students, the ideal method; the rest use other methods, such as studying changes in schoolwide performance. Of these 21 studies:

  • Nine find that overall gains in charter schools were larger than other public schools
  • Three find higher charter gains in certain categories of schools, such as those serving at-risk students
  • Six find comparable gains in charter and traditional public schools
  • Three find that charter schools' overall gains lagged behind
  • Of the seven studies that examine whether charter schools improve with age, five find charters improve over time; and two find no significant differences between older and younger charter schools.

  • We need better research about how well students in charter schools are performing.
  • We need more research on why some charters so outperform other charter and non-charter schools.
  • We need much more attention focused on evaluating chartering as a policy. Knowing how well charter school students on average are performing does not answer the most important questions policymakers have about where to go with their charter policies.
  • Charter schooling represents an experiment worth continuing and refining to improve quality further over time.

    For the full paper, please see Charter Achievement Report under CSLC Resources.