A group of education advocates is calling on the District to release more information about students’ performance on city tests, arguing that the limited data released in years past has overstated city schools’ progress.

Elaine Weiss of the Broader, Bolder Approach to Education — a group that has been critical of education policies that have taken root in the District, such as charter schools and test-based accountability — wrote in an analysis to be released Thursday that “lack of transparency, combined with cherry-picking specific numbers” has enabled the city to “paint a false picture of progress,” particularly among poor and African American students.

The call for more detailed information comes as the Office of the State Superintendent of Education prepares to release scores on the 2014 city tests — known as the D.C. CAS — in August.

OSSE officials say they do plan to release additional test score data this year in an effort to be more transparent. But spokesman Briant Coleman said the agency “strongly disagrees” with Broader, Bolder’s report, which he said contained “numerous errors and inaccurate information.”

“We stand by the validity and reliability of the DC-CAS,” Coleman wrote in an e-mail. “We appreciate the work and progress our students continue to make.”

OSSE annually releases data showing the percentage of students who fall into each of four categories on the test: below basic, basic, proficient and advanced. In 2013, the percent of children considered proficient or above jumped four points, gains that Chancellor Kaya Henderson and Mayor Vincent C. Gray (D) celebrated as historic.

Weiss argues that D.C. CAS proficiency rates are an ineffective way to assess student progress because the definition of “proficiency” is vague.

D.C. CAS tests are scored on a 99-point scale, and students are deemed proficient if they meet or exceed a “cut score” set by educators and test developers. Last year, D.C. teachers recommended setting a new and higher bar for proficiency to reflect higher expectations of students under the Common Core State Standards. OSSE quietly decided not to adopt the new bar — which would have resulted in lower proficiency rates — in order to maintain the comparability of scores over time.

Weiss said the city should release students’ underlying test scores, separated by race, poverty and disability status.

Those underlying scores show that during the past few years, the city has made less progress than leaders have claimed and that gaps between white and black children, and poor and low-income children, are growing across many grade levels, according to Weiss’s analysis.

OSSE officials said they plan to release underlying scores for each school and student subgroup for the first time this year.

The District made the largest gains in the country on the 2013 National Assessment of Educational Progress, supporting the gains that city leaders announced on the 2013 CAS. But Weiss — echoing D.C. Council members, D.C. activists and others — said the NAEP gains masked growing achievement gaps and were driven by demographic change as city schools enrolled more high-scoring white students.

Melissa Salmanowitz, a D.C. schools spokeswoman, said the school system is confident in the accuracy of D.C. CAS results that showed widespread gains.

“It’s incredibly disappointing that this group refuses to believe what is clear in the D.C. CAS data, that our students are making historic progress,” she said. “They’re using fuzzy math and distortions to create a narrative that simply is not true. Every indicator, from test scores to attendance to student satisfaction, shows how DCPS is moving in the right direction.”