The math and reading performance of third-grade students in D.C. public schools has not significantly improved since 2007, according to a new study of the city’s standardized test scores released Monday by a nonprofit advocacy group.

HyeSook Chung, executive director of D.C. Action for Children, said her group’s analysis should prompt city officials to examine whether the education reforms initiated five years ago by former chancellor Michelle A. Rhee are succeeding.

“The claim that we’re hearing from the city is that we’re seeing huge improvements, but we started doing some preliminary analysis and we were not seeing those same improvements,” Chung said.

The proportion of D.C. students who are proficient in math and reading has risen since 2007, but proficiency rates don’t tell the whole story, Chung said. Her group analyzed the test scores using a method meant to capture a more fine-grained snapshot of student performance between 2007 and 2011.

Researchers used a weighted formula that scored schools based on the number of students in each test performance category: below basic, basic, proficient or advanced. Schools received between one and four points for each student, based on the student’s performance category.

The average weighted reading score for D.C. public schools fell from 2.26 to 2.19 between 2007 and 2011, while the average weighted math score rose from 2.14 to 2.2. Both changes were statistically insignificant.

The study also found no evidence of significant gains in public charter schools. Charter schools have higher average proficiency rates than traditional public schools, but Monday’s analysis found no significant difference between the two sectors.

The group analyzed third-grade scores because research shows that students who don’t read proficiently by the end of third grade are less likely to graduate from high school.

Pedro Ribeiro, a spokesman for Mayor Vincent C. Gray (D), said that focusing on third-grade performance misses the growth that students make later in school. Students in third grade in 2007 made double-digit proficiency gains in both math and reading by the time they reached eighth grade, he said.

But Ribeiro agreed with the report’s recommendation that the city continue its efforts to provide high-quality preschool to all children, a priority of the mayor’s. A city analysis released earlier this year showed that students who enrolled in pre-kindergarten fared better on third-grade tests than students who had not.

“There is strong data that indicates that if more students participate in pre-K programs our state proficiency rate would substantially rise to higher levels,” Ribeiro wrote in an e-mail.

The study released Monday is part of the long-running D.C. Kids Count project funded by the Annie E. Casey Foundation. D.C. Action for Children conducted the analysis with the help of Elder Research Inc., a Charlottesville-based firm.