The dean of the Milken Institute of Public Health on Saturday negated President Donald Trump’s claims that the school’s research estimating 3,000 deaths in Puerto Rico after Hurricane Maria was driven by partisan politics.

Lynn Goldman, the dean of the public health school, said in a Washington Post op-ed that “politics played no role” in the study, which was commissioned by the Puerto Rican government in February and released last month. Trump disputed the findings in a series of tweets Thursday and Friday, falsely claiming that the estimate was “done by the Democrats” to “make me look as bad as possible.”

“To set the record straight, our study was carried out with no interference whatsoever from any political party or institution,” she wrote.

Public health school researchers analyzed death certificates from the six months following Hurricane Maria’s landfall in Puerto Rico in September 2017. They used a mathematical model to compare the number of deaths over the months following the hurricane to mortalities in years without a storm.

The study also accounted for displacement after the hurricane.

Goldman started the op-ed with an anecdote about receiving a call from Puerto Rico Gov. Ricardo Rosselló last December to discuss the hurricane. She said she knew the number of deaths “was, and would continue to be, a highly charged issue”– but that she didn’t know “the issue would be the subject of several presidential tweets.”

The op-ed described Milken’s methodology behind the study and compared its findings to that of other institutions, like Harvard and Penn State universities, which released interim estimates of 1,139 and 4,645 deaths through December 2017, respectively. Goldman said Harvard’s study, which was based on a household survey, didn’t adjust household deaths for household size.

“Ours was the only study that took into account the enormous net out-migration of citizens that occurred after the storm,” she wrote.

Goldman added that Milken researchers “don’t know the exact circumstances” around the deaths of each person because many factors contributed to the death toll, including lack of transportation or access to water and food.

“What was lacking was adequate planning and preparedness for such a horrific storm,” Goldman said. “No one administration or political party is responsible for why we still don’t prioritize preparedness even though we are increasingly threatened by large hurricanes.”