The estimated number of above-average “excess deaths” in Puerto Rico attributed to Hurricane Maria (Sept 20, 2017) is a difficult figure to estimate objectively. Puerto Rico’s official figure of 64 deaths by December 9, 2017 (which the President remembered) counted only those deaths directly attributed to the storm and confirmed by medical examiners. Most of the direct deaths from Katrina were from drowning – which is much easier to attribute to the storm than many other causes of death. Studies of Puerto Rican deaths from Maria aspire to account for a wide range of indirect effects that are presumed (not proven) to be consequences of the storm such as suicides and heart attacks, infectious diseases, and damage to electricity and therefore to dialysis and respirator equipment.
Among at least eight major studies of direct and indirect effects on mortality attributed to Maria, two outliers stand out as being 3-5 times larger than the others, which all cluster around 1000. The first big number was from Harvard. On September 13, Time said, “Harvard’s report, which was based on systematic household surveys throughout Puerto Rico, reached an estimate of 4,645 storm-related deaths between September and December 2017, many as a result of ‘delayed or interrupted health care.’” Nonsense. The Harvard study extrapolated from only 15 deaths reported in a survey of 3299 households to estimate that “between 793 and 8498 people died … up to the end of 2017.” By adding 793 and 8498 and dividing the result by 2, Time and others came up with a totally meaningless “average” which were widely reported with predictable sensationalism: “The hurricane that struck Puerto Rico in September was responsible for more deaths than the Sept. 11 attacks and Hurricane Katrina combined,” exclaimed The Daily Beast.” In reality, these “estimates of death from people who were interviewed” are little better than an opinion poll, and finding 15 deaths out of a sample of 3299 can’t plausibly be multiplied into 4645 for the whole island.
The latest sensational estimate of 2,975 excess deaths over six months is from an August 28 report from the Milken Institute School of Public Health at George Washington University (GWU) commissioned by the Government of Puerto Rico. The study mentions two “scenarios” (census and displacement) yet only publicized the one with the biggest number: “Total excess mortality post-hurricane using the migration displacement scenario is estimated to be 2,975 (2,658-3,290) for the total study period of September 2017 through February 2018.”
The 2,975 estimate only applies to the “displacement scenario.” That is, the study “estimates cumulative excess net migration from Puerto Rico in the months from September 2017 through February 2018 and subtracts this from the census population estimates in these months.” The population fell by about 8%, mainly due to migration rather than death, so the fact that there were more deaths than average after the hurricane means the death rate (deaths per thousand) rose more than the unadjusted statistics would suggest because the population is smaller. But this issue is the number of deaths, not the death rate, and displacement (migration) did not make that number any higher than half a dozen other studies found (about 1000) much less three times higher.