In 2010, Schools Chancellor Michelle Rhee gets applause from Mayor-elect Vincent Gray, left, Mayor Adrian Fenty and interim schools chancellor Kaya Henderson at a news conference where Rhee announced her resignation. (Ricky Carioti/THE WASHINGTON POST)

The District’s public schools have made promising improvements after seven years of intensive reforms, but many disparities persist in academic resources and performance between poor and affluent students, according to the National Research Council.

In a much-anticipated report released Wednesday, the council offers an independent evaluation of the effects of sweeping school reform measures put in motion in 2007, when then-Mayor Adrian M. Fenty took control of the city’s schools and appointed Michelle A. Rhee as schools chancellor.

The council said that the District’s poor and minority students are still far less likely to have a quality teacher in their classrooms, perform at grade level and graduate from high school in four years. Although performance on standardized tests has improved for all groups, the city’s academic achievement gap has not diminished.

Rhee’s efforts to change the schools attracted national attention as she clashed with union leaders and vowed to upend the status quo. Many urban school systems have regarded some of the changes, including new teacher evaluations and academic standards, as models. But what researchers told the D.C. Council’s Education Committee on Wednesday is that there are no quick solutions and that many years of hard work remain ahead.

“Patience is of great importance in all these endeavors,” said Diana C. Pullin, professor of educational leadership and higher education at Boston College, who helped write the report.

The report recommends that the city make addressing disparities its primary objective. It emphasizes a need for more centralized data collection across all D.C. public schools, including charters, which now enroll 44 percent of the city’s public school students. The data would be maintained by a single agency that has ultimate responsibility for monitoring and overseeing the quality of public education.

Currently, multiple agencies with confusing missions and lines of authority report different information in multiple formats, and the report’s authors were often unable to obtain information they sought. Such gaps in data make it difficult to draw basic comparisons between charter and traditional schools or to meet the needs of struggling students, the authors said.

“What we know about urban school reform efforts around the country is that a comprehensive look at data is often the beginning of sustained school reform efforts,” said Carl Cohn, director of the Urban Leadership Program at Claremont Graduate University and co-chairman of the committee that wrote the report.

Jennifer C. Niles, deputy mayor for education, said she agrees with many of the report’s findings. She said the city is making some headway in clarifying lines of authority and has made better coordination a priority. As of this year, Schools Chancellor Kaya Henderson reports to her instead of directly to the mayor. And the city plans to announce a new “cross-sector task force” charged with improving coherence across all public schools.

Scott Pearson, executive director of the D.C. Public Charter School Board, said the board is taking part in collaborative efforts such as LearnDC, which compiles information about college and career readiness.

The report is agnostic about which agency should host a common “data warehouse,” although it said that in most places that role would fall to a state agency. In the District, the Office of the State Superintendent of Education (OSSE) is not “consistently functioning as an effective state education authority and has not yet earned the full confidence of officials in other agencies who rely on it,” the report said.

The National Research Council of the National Academies is an independent organization chartered by Congress. The committee that assembled the evaluation included professors and other researchers with expertise in school reform. A series of reports produced by DC EdCore, a consortium of research institutions led by George Washington University, were included as part of the research base.

The D.C. Public Education Reform Amendment Act of 2007, which called for the independent evaluation, set up a new governance structure that replaced the local Board of Education with a State Board of Education removed from day-to-day oversight, and created OSSE and a deputy mayor for education.

Rhee had unusual flexibility to make changes to the city’s school system. She pursued many strategies prominent in the national school reform movement, including new recruitment, evaluation and compensation schemes for teachers, uniform academic standards, and heightened accountability for schools through tests and other measures.

The main policy outlines have changed little in the intervening years despite the departure of Rhee and Fenty, a new chancellor and two subsequent mayors.

Cohn said that the stability in leadership and vision is “cause for hope” for long-term improvements.

Overall, test scores for all public school students improved in local and national standardized tests. The portion of all students scoring proficient or above in reading and math on the District’s standardized tests increased between 2007 and 2014, with larger gains in math than in reading.

Test scores have improved for all students, but about 60 percent of black and economically disadvantaged students in the city’s traditional schools score below proficient in both subjects, and have seen only small improvements over time. The report called these results “disturbing.”

While graduation rates are on the rise nationally, they have fluctuated in the District and remain much lower for male students, poor students and special-education students.

Ernestine Benedict, chief of communications for D.C. public schools, said officials are working “urgently” to address the achievement gap through new initiatives focused on males of color, investments in more Advanced Placement courses at every high school, and the introduction of more-challenging lesson plans for all classrooms next year.

“While we have much work yet to do, the NRC evaluation makes it clear that there is a great deal of success to build on,” she said.

The most polarizing of the post-2007 changes was the creation of a teacher evaluation system, known as IMPACT, that led to the dismissal of more than 400 teachers in its first years. It was later extended to evaluate principals.

The system, which includes measures for performance and opportunities for feedback and support, reflects research on teacher evaluations, the researchers found.

The school system’s efforts to improve teacher quality are falling short in many schools, however, because effective teachers are distributed unevenly across wards or even within wards, with fewer talented teachers working in the highest-poverty schools.

The report said there is no systematic information reported about the quality of teachers in charter schools, and it said additional information would help policymakers and parents understand disparities.