One of the Obama administration’s signature efforts in education, which pumped billions of federal dollars into overhauling the nation’s worst schools, failed to produce meaningful results, according to a federal analysis.

Test scores, graduation rates and college enrollment were no different in schools that received money through the School Improvement Grants program — the largest federal investment ever targeted to failing schools — than in schools that did not.

The Education Department published the findings on the website of its research division on Wednesday, hours before President Obama’s political appointees walked out the door.

“We’re talking about millions of kids who are assigned to these failing schools, and we just spent several billion dollars promising them things were going to get better,” said Andy Smarick, a resident fellow at the American Enterprise Institute who has long been skeptical that the Obama administration’s strategy would work. “Think of what all that money could have been spent on instead.”

The School Improvement Grants program has been around since the administration of President George W. Bush, but it received an enormous boost under Obama. The administration funneled $7 billion into the program between 2010 and 2015 — far exceeding the $4 billion it spent on Race to the Top grants.

[Feds spent $7 billion to fix failing schools — with mixed results]

The money went to states to distribute to their poorest-performing schools — those with exceedingly low graduation rates, or poor math and reading test scores, or both. Individual schools could receive up to $2 million per year for three years, on the condition that they adopt one of the Obama administration’s four preferred measures: replacing the principal and at least half the teachers, converting into a charter school, closing altogether, or undergoing a “transformation,” including hiring a new principal and adopting new instructional strategies, new teacher evaluations and a longer school day.

The Education Department did not track how the money was spent, other than to note which of the four strategies schools chose.

Arne Duncan, Obama’s education secretary from 2009 to 2016, said his aim was to turn around 1,000 schools every year for five years. “We could really move the needle, lift the bottom and change the lives of tens of millions of underserved children,” Duncan said in 2009.

Duncan often said that the administration’s school-improvement efforts did not get the attention they deserved, overshadowed by more-controversial efforts to encourage states to adopt new standards and teacher evaluations tied to tests.

The school turnaround effort, he told The Washington Post days before he left office in 2016, was arguably the administration’s “biggest bet.”

[Days from leaving office, Duncan talks successes, failures]

He and other administration officials sought to highlight individual schools that made dramatic improvements after receiving the money. But the new study released this week shows that, as a large-scale effort, School Improvement Grants failed.

Just a tiny fraction of schools chose the most dramatic measures, according to the new study. Three percent became charter schools, and 1 percent closed. Half the schools chose transformation, arguably the least intrusive option available to them.

“This outcome reminds us that turning around our lowest-performing schools is some of the hardest, most complex work in education and that we don’t yet have solid evidence on effective, replicable, comprehensive school improvement strategies,” said Dorie Nolt, an Education Department spokeswoman.

Nolt emphasized that the study focused on schools that received School Improvement Grants money between 2010 and 2013. The administration awarded a total of $3.5 billion to those schools, most of it stimulus funds from the American Recovery and Reinvestment Act of 2009. “Since then,” she said, “the program has evolved toward greater flexibility in the selection of school improvement models and the use of evidence-based interventions.”

Some education experts say that the administration closed its eyes to mounting evidence about the program’s problems in its own interim evaluations, which were released in the years after the first big infusion of cash.

The latest interim evaluation, released in 2015, found mixed results, with students at one-third of the schools showing no improvement or even sliding backward.

Even then, Duncan remained optimistic about the School Improvement Grants, which he said had — along with the Race to the Top grants — unleashed innovation across the country. Speaking about the two grant programs at a fast-improving high school in Boston in 2015, he argued that it would take time to see and measure their full effects.

“Here in Massachusetts, it actually took several years to see real improvement in some areas,” Duncan said at the time. “Scores were flat or even down in some subjects and grades for a while. Many people questioned whether the state should hit the brakes on change. But you had the courage to stick with it, and the results are clear to all.”

[Betsy DeVos lauded as a bold reformer, also called unfit for the job]

Smarick said he had never seen such a huge investment produce zero results.

That could end up being a gift, he said, from Duncan to Betsy DeVos, President-elect Donald Trump’s nominee for education secretary and a prominent proponent of taxpayer-supported vouchers for private and religious schools.

Results from the School Improvement Grants have shored up previous research showing that pouring money into dysfunctional schools and systems does not work, Smarick said: “I can imagine Betsy DeVos and Donald Trump saying this is exactly why kids need school choice.”