Charter schools may be gaining popularity among communities looking for alternative education solutions, but Connecticut’s largest teacher’s union and a New Haven-based nonprofit disagree as to whether or not they are effective.

At the heart of the argument is a pair of dueling reports on public education. A September report released by the nonprofit Connecticut Coalition for Achievement Now, or ConnCan, identified a large achievement gap between charter schools and “traditional” public schools. But a January report by the Connecticut Education Association, the teacher’s union, rebutted ConnCan’s finding and argued that the performance of charter schools varies as much as the performance of different public schools.

Marc Porter Magee, the director of communications and research for ConnCan, said charter schools have done a better job helping their students perform on tests than public or magnet schools have. For example, the ConnCan report indicates that there is a 10-point difference between the performance gain of charter middle schools and public magnet middle schools.

In its report, which uses data provided by the government, ConnCan does not draw any explicit conclusions as to why charter schools seemed to outperform their counterparts in these areas, or why they take up 13 percent of the slots in the study, though only 1.2 percent of schools in the state are charter schools.

The CEA report contests ConnCan’s conclusions, saying that “the achievement levels, improvement and performance gains displayed by magnet and charter schools are approximately as varied as are those displayed by traditional schools.”

Peter Behuniak, the lead researcher for the CEA study and a professor at the Neag School of Education at the University of Connecticut, said ConnCan’s study was too small to make their findings meaningful because over 60 percent of the data was unavailable in some areas.

“The missing information was so substantial as to render a meaningful interpretation of the ConnCann study almost impossible,” he said.

The report also stated that ConnCan failed to address issues of student turnover at schools and does not separate schools out by size in order to more fully represent its findings.

It is unclear what effect the reports will have on education policymaking in the state. Catherine Sullivan-De Carlo, a spokesperson for the New Haven Public Schools, said she was vaguely aware of the research, though she does not feel any changes are needed in the state’s approach to public education.

“The state legislature authorized charter schools as a way to try out some strategies, to see what works and to replicate it in the public school system,” she said. “And I think that’s the way it should stay.”

Ward 7 Alderwoman Frances Clark said that while she thinks charter schools are “wonderful,” she did not know if their model could be replicated for large school systems.

“I don’t believe you can have an entire city of charter schools,” she said. “Can you find numbers of people who will work into the middle of the night, who will have an extended school day? I don’t think you can. And the most important thing is, not every one of them is successful.”

Clark said the Board of Aldermen will travel to New York in February to look at a KIPP public charter school there.