The estimated number of casualties in Gaza could be less than 25,000 dead, the study says

Deaths from bombs and other traumatic injuries during the first nine months of the Gaza war may have been underestimated by more than 40 percent, according to new analysis published in The Lancet.

The peer-reviewed statistical analysis, led by epidemiologists from the London School of Hygiene and Tropical Medicine, used modeling in an effort to provide an objective estimate of third-party casualties. The United Nations relies on a figure from the Hamas-run Health Ministry, which it says is mostly accurate, but which Israel criticizes as inflated.

But a new analysis suggests that the number for Hamas’ health ministry is significantly lower. The researchers concluded that the death toll from Israel’s aerial bombardment and military ground operation in Gaza between October 2023 and the end of June 2024 was about 64,300, not the 37,900 reported by the Palestinian Ministry of Health.

The estimate in the analysis corresponds to 2.9 percent of Gaza’s prewar population suffering from traumatic injuries, or one in 35 residents. The analysis did not take into account other war-related casualties, such as deaths from malnutrition, water-borne diseases or the breakdown of the health system as the conflict progressed.

The study showed that 59 percent of the dead were women, children and people over 65 years old. It has not been determined what proportion of the reported dead are combatants.

Mike Spagat, an expert in calculating war casualties who was not involved in this research, said the new analysis convinced him that casualties in Gaza were underestimated.

“This is good evidence that the real number is higher, probably significantly higher, than the official figures of the Ministry of Health, higher than I thought in the last few months,” said Dr. Spagat, who is a professor at Royal Holloway College, University of London.

But presenting precise figures, such as the 41 percent unreported death rate, is less helpful, he said, since the analysis actually shows the actual total could be lower or significantly higher. “Quantitatively, it’s much more uncertain than I think it appears in the papers,” said Dr. Spaghetti.

The researchers said their estimate of 64,260 deaths from traumatic injuries had a “confidence interval” of between 55,298 and 78,525, meaning the actual number of victims was likely within that range.

If the estimated level of underreporting of deaths by June 2024 is extrapolated to October 2024, the total number of casualties in Gaza in the first year of the war would exceed 70,000.

“There is an importance of war-related deaths because it speaks to the question of whether the campaign is proportionate, whether, in fact, sufficient measures are taken to avoid civilian casualties,” said Francesco Checchi, an epidemiologist with expertise in conflicts and humanitarian crises and a professor at the London School of Hygiene and Tropical Medicine who was the author of the study. “I think commemorating is important. There is inherent value in trying to get the right number.”

The analysis uses a statistical method called recapture analysis, which has been used to estimate casualties in other conflicts, including the civil wars in Colombia and Sudan.

For Gaza, the researchers used three lists: the first is a register maintained by the Palestinian Ministry of Health, which consists mainly of the dead in hospital morgues, and an estimate of the number of unextricated people buried in the rubble. Others are deaths reported by family or community members through an online survey the ministry set up on January 1, 2024, when the pre-war death registration system broke down. Palestinians inside and outside Gaza were asked to provide names, ages, national identification numbers and places of death for the victims. A third source was the obituaries of people who died from injuries that were posted on social media, which did not necessarily contain all the same biographical information and were compiled by hand by the researchers.

The researchers analyzed these sources to look for individuals appearing on multiple kill lists. A high level of overlap would suggest that several deaths were uncounted; the low amount they found suggested otherwise. The researchers used models to calculate the probability that each individual would appear on any of the three lists.

“The models allow us to really estimate the number of people who are not registered at all,” said Dr. Checchi. That, combined with the listed number, gave the analysts’ tally.

Patrick Ball, director of research at the Human Rights Data Analysis Group and a statistician who has done similar estimates of violent deaths in conflicts in other regions, said the study is powerful and well-reasoned. But he cautioned that the authors may have underestimated the amount of uncertainty caused by the ongoing conflict.

The authors used different variations of mathematical models in their calculations, but Dr. Ball said that instead of presenting a single figure — 64,260 deaths — as an estimate, it may have been more appropriate to present the number of deaths as a range of 47,457 to 88,332 deaths, a range that encompasses all the estimates obtained by modeling the overlap between the three censuses.

“It’s really hard to do things like this in the middle of a conflict,” said Dr. Ball. “It takes time and it takes access. I think you could say the range is higher and that would be acceptable.”

While Gaza had a robust death registration process before the war, it now has only a limited function following the destruction of much of the health system. Deaths are not counted when entire families are killed at once, leaving no one to report, or when an unknown number of people die in the collapse of a large building; Residents of Gaza are increasingly being buried near their homes without going through the morgue, said Dr. Checchi.

The authors of the study acknowledged that some of those presumed dead were actually missing, most likely captured in Israel.

Roni Caryn Rabin and Lauren Leatherby contributed reporting.