In a visit to the island around two weeks after Hurricane Maria, when the official death toll stood at 16, President Trump contrasted the number with the “hundreds and hundreds of people that died” after Hurricane Katrina. “Everybody watching can really be very proud of what’s taken place in Puerto Rico,” he said.

The new research, which was performed independently of the government, compared the actual death rate with what would have been expected had the storm not occurred — a method used in several earlier analyses. In December, The New York Times found that 1,052 more people than usual died in the 42 days after Hurricane Maria made landfall.

A study by Harvard researchers published in The New England Journal of Medicine earlier this year estimated the death toll could range from 800 to more than 8,000 people, and was based on a household survey.

The results of the new study make clear what the government had recognized even before the official expansion of the death toll, officials said on Tuesday.

“Hurricane Maria was a catastrophe of historic proportions, as never seen or lived before in the United States,” Carlos Mercader, executive director of the Puerto Rico Federal Affairs Administration, said in an emailed statement. He said the new analysis “is sobering, and its insights make clear that Congress and FEMA must work with us to establish a better system for the preparation and distribution of supplies ahead of future disasters.”

The George Washington University researchers released very few details of their methodology or analysis, making it difficult to assess the quality of their work, which was carried out at a cost of $305,000 and also included an analysis of how the government certified deaths and communicated about them. They wrote that “national and international experts in different fields” had reviewed their methods. The report has not yet been subjected to the more rigorous process of being published in a peer-reviewed medical journal, though it has been submitted for publication.