Arizona students enrolled in charter schools for two or three consecutive years showed stronger gains on reading tests than their counterparts in traditional public schools, according to a study released last week.
The study, sponsored by the Goldwater Institute, also showed that students in charter schools for two years showed a slight test-score advantage in mathematics over similar students in traditional public schools.
However, students in charter schools for three years had slightly lower gains in math than their counterparts in regular public schools. Arizona has the largest number of charter schools in the nation, with more than 400 of the publicly financed but administratively independent schools.
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“In sum, charter schools do consistently better in reading,” concludes the report by the Phoenix think tank, which supports charter schools. “They do no worse in math, and in some specifications, charters do better in math as well.”
The study’s lead author was Lewis C. Solmon, a former dean of the graduate school of education at the University of California, Los Angeles who is now a adjunct fellow at the Goldwater Institute. The co-authors were David Garcia, the director of research and evaluation in the Arizona education department, and Kern Paark, a doctoral candidate in economics at Arizona State University.
The researchers studied data from the state’s administration of the Stanford Achievement Test-9th Edition to virtually all students in traditional public schools and charter schools since 1997. The study sample started with some 63,000 students enrolled in grades 3-12 in the 1996-97 school year.
Mixed Findings on Math
In reading, students enrolled in charter schools for two consecutive years showed a 2.35 to 2.44 extra point advantage on the Stanford-9 over students enrolled in traditional public schools for two years. Students in charter schools for three years in a row showed an additional 1.31 point advantage. Such gains are statistically significant, the researchers said.
The picture was a little different in math. Under some models of analyzing the data, charter students gained more in math. But under one model, they showed only modest gains after spending two years in charter schools, and a slight decline after three years. The authors suggest that charter schools might have a harder time than traditional public schools in hiring and retaining good math teachers.
Mary Gifford, the director of the institute’s Center for Market-Based Education, said the researchers took pains to analyze the data using several models so that their findings would stand up to criticism from charter opponents.
“We have really tried to slice and dice the data any way we could to make sure the results are the same from model to model,” said Ms. Gifford, who is a former executive director of Arizona’s state charter school board and currently a member of that board.
The test-score gains amount to an educational effect of about one extra month of school per year, she said.
“Charter schools are more bang for your buck,” she argued. “You’re getting more achievement for less money in charter schools than in traditional public schools.”
About 14 percent of Arizona public school students were enrolled in charter schools in 1999, the third year studied. The study says charter schools received about $4,500 in per- pupil spending, compared with $7,000 for traditional public schools.
Ms. Gifford said she was heartened by the study’s findings on student mobility.
Many educators argue that mobility hampers achievement, but the study found that even students who moved among charter schools during the three years gained more in reading and math than students who stayed in traditional public schools.
