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Charter-School Management Organizations: Diverse Strategies and Diverse Student Impacts
Initial registration date
February 24, 2015
February 24, 2015 1:56 PM EST
Mathematica Policy Research
Other Primary Investigator(s)
Mathematica Policy Research
Additional Trial Information
The National Study of CMO Effectiveness is a longitudinal research effort designed to measure how nonprofit charter school management organizations (CMOs) affect student achievement and to examine the internal structures, practices, and policy contexts that may influence these outcomes. The study examines CMO impacts on student achievement in middle school, high school graduation, and postsecondary enrolment using quasi-experimental methods for a large sample of schools. In a smaller sample of oversubscribed schools, we obtain experimental CMO impacts in elementary, middle and high schools using lottery data.
Gill, Brian and Joshua Haimson. 2015. "Charter-School Management Organizations: Diverse Strategies and Diverse Student Impacts." AEA RCT Registry. February 24.
The intervention is the offer to attend an oversubscribed charter-school management organization (CMO) school. CMOs establish and operate multiple charter schools, representing one prominent attempt to bring high performance to scale. Many CMOs were created in order to replicate educational approaches that appeared to be effective, particularly among disadvantaged students.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
For middle and high schools, the outcomes are math and reading test scores one year after baseline. For elementary schools, the outcomes are math and reading test scores four years after baseline.
Primary Outcomes (explanation)
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
CMO schools with more applicants than available seats often admit students using a random lottery. Records from these lotteries can be used to conduct a randomized experiment as students who participated are offered CMO admission completely by chance. Experimental treatment and control status was determined by whether the student received an admission offer at the time of the lottery.
Experimental sites had to meet each of the following criteria to be included in the analysis:
1. Low student attrition. Specifically, the overall and differential attrition rates must be lower than the What Works Clearinghouse maximum thresholds (liberal attrition standard);
2. Valid randomization. If we did not observe the lottery and consequently were unsure of the randomization validity, any difference between treatment and control average baseline test scores must be less than 0.25 standard deviations and demographicdifferences must be less than 25 percentage points
3. Higher treatment group CMO enrollment. The difference in CMO school enrollment between treatment and control groups must be at least 20 percent.
Experimental Design Details
Randomization conducted by individual schools.
The unit of randomization is the student.
Was the treatment clustered?
Sample size: planned number of clusters
16 schools across 7 sites, where sites are groups of schools that shared applicants. Grouping schools into sites was necessary as treatment was defined as receiving an offer to any CMO school.
Sample size: planned number of observations
Elementary schools: 64 treatment students, 54 control students; Middle schools: 331 treatment students, 551 control students; High schools: 214 treatment students, 214 control students
Sample size (or number of clusters) by treatment arms
16 schools across 7 sites (both treatment and control)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
INSTITUTIONAL REVIEW BOARDS (IRBs)
P/PV Institutional Review Board
IRB Approval Date
IRB Approval Number
Post Trial Information
Is the intervention completed?
Is data collection complete?
Data Collection Completion Date
Final Sample Size: Number of Clusters (Unit of Randomization)
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
Final Sample Size (or Number of Clusters) by Treatment Arms