To arrive at the 2,975 figure, the study looked at historical death patterns from 2010 to 2017 to estimate how many people would have died had Hurricane Maria not hit the island. That figure was then compared to the actual number of deaths from September 2017 through February 2018 — obtained in records provided by the Puerto Rico Vital Statistics Records division of the Puerto Rico Department of Health — to determine what the report describes as the “estimate of excess mortality due to the hurricane.”

The study found that while all age groups and social strata were affected by the hurricane, the risk of death was “45% higher and persistent until the end of the study period for populations living in low socioeconomic development municipalities.”

It also found that men age 65 and older were at heightened risk of death through February, the end of the study period.