The levees of the Red River in Grand Forks, North Dakota, are built to withstand 51-ft water levels. In 1997, the National Weather Service predicted a flood, but despite a 35% margin of error for previous estimates, it emphasized that the river would crest at 49 ft at most. When the waters rose to 54 ft, wreaking havoc on the area, local inhabitants were shocked and angry. Why had forecasters projected such confidence in their prediction? According to Nate Silver, who describes the incident in The Signal and the Noise, “The forecasters later told researchers that they were afraid the public might lose confidence in the forecast if they had conveyed any uncertainty in the outlook.”
Rosenbaum, Lisa. “Communicating Uncertainty — Ebola, Public Health, and the Scientific Process.” New England Journal of Medicine, November 13, 2014. doi:10.1056/NEJMp1413816.