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Government officials bad at math make bad evacuation orders

Christian Fernsby |
New research suggests that emergency management officials often do not have the numeracy skills needed to make the best decisions which residents to evacuate during a hurricane and when to make the decision.

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The study, published online Aug. 30 in the Bulletin of the American Meteorological Society, showed that the most numerate officials were almost twice as likely as less numerate ones to provide additional evacuation times to their coastal communities. Less numerate ones, on the other hand, gave their communities less advance warning, and when they finally did issue evacuations, over-evacuated tens of thousands more people.

And, the study found, federal agencies need to supply emergency management officials with the most complete information available in order for them to make the best choices for people who live in a disaster's path.

The study involved 81 emergency managers and other public safety officials predominantly from coastal states that are affected by hurricanes, as well as 227 Ohio State graduate and upper-division students from related fields of study. The researchers began their experiments by testing each subject's ability to make decisions using probability and statistics—a sort of baseline math test that allowed them to evaluate each participant's numeracy. In other words, how well they understood the ways probability and statistics might play out in the real world.

Researchers then provided the study participants with a scenario based on a real storm—Hurricane Rita in 2005. Rita was among the strongest hurricanes ever recorded in the Gulf of Mexico, hitting land near the Louisiana-Texas border, killing 120 people and causing an estimated $18.5 billion in damages. Participants were not told the scenario was based on Rita, so they could not use any knowledge of the storm to guide their decisions.

Participants were randomly assigned to treatments with varying amounts of information about the approaching storm. Some subjects received a great deal of information, including the forecasted track and potential alternative tracks; others received limited information.

The researchers asked study participants to determine whether to evacuate, when to evacuate and whom to evacuate. Decisions were structured to coincide with the release of advisories from the National Hurricane Center (NHC).

Basing the experiments on a real disaster allowed researchers to determine which choices were "good." Because the outcome was known to the researchers, they could evaluate the areas affected—those that either under-evacuated or over-evacuated regions.

The researchers found that people who scored well on the baseline math test made better choices on behalf of the community.

People with higher numeracy issued evacuation orders that gave people more time to leave the storm's path.

People who have the practical ability to evaluate and understand risk ordered evacuations in the simulated disaster about nine hours earlier than people who did not have that skillset, the study found.

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