In a May 2016 doctoral dissertation titled, “A Complexity Context to North Carolina Charter School Classroom Interactions and Climate: Achievement Gap Impacts,” Liz Johnson conducted an analysis of the “relationship between classroom climate, interactions, and student achievement, through a complexity systems context.”

Using some pretty high-level quantitative and qualitative methods, Johnson concluded,

According to the findings of this study, North Carolina charter schools have served as a successful reform strategy to address the achievement gap problem in North Carolina, with school-specific strategies including high teacher support, students’ teaching students, IAP/tutoring/online supplemental program, and small classrooms. All schools, on average, scored 30.9% to 56.8% higher on grade-level proficiency (GLP) than the North Carolina 2014-2015 average.

Charter schools, as a reform, were established with the goal of narrowing the achievement gap (Cheng et al., 2015). The schools in this study contributed to narrowing the gap. The study was very limited in the sample size and provided no comparisons with traditional public schools in the same urban area. The schools in the sample were not representative of North Carolina averages in racial make-up and number of free-lunch students. When regressions were run, however, there was no statistical difference in achievement scores based on race or free-lunch status. The results in this study were in opposition to Spring and Hanson’s (2015) and Ramey’s (2015) assertions that charter schools harm children. Eisen and Ladd (2015) claimed that charter schools did not fulfill their promise of keeping class sizes to 18 or fewer. Of the 16 classes in the study, 8 had class sizes of 18 or fewer. The average class sizes for the schools ranged from 10 to 24.

As encouraging as they results were, the study was pretty limited.  Johnson examined only eighth-grade mathematics teachers and students at four urban charter schools in a North Carolina.