The Signal and the Noise: Why So Many Predictions Fail-but Some Don't

by Nate Silver

By late fall, another problem had emerged, this one far more serious. About five hundred patients, after receiving their shots, had begun to exhibit the symptoms of a rare neurological condition known as Guillain–Barré syndrome, an autoimmune disorder that can cause paralysis. This time, the statistical evidence was far more convincing: the usual incidence of Guillain–Barré in the general population is only about one case per million persons.22 In contrast, the rate in the vaccinated population had been ten times that—five hundred cases out of the roughly fifty million people who had been administered the vaccine. Although scientists weren’t positive why the vaccines were causing Guillain–Barré, manufacturing defects triggered by the rush production schedule were a plausible culprit,23 and the consensus of the medical community24 was that the vaccine program should be shut down for good, which the government finally did on December 16. In the end, the outbreak of H1N1 at Fort Dix had been completely isolated; there was never another confirmed case anywhere in the country.25 Meanwhile, flu deaths from the ordinary A/Victoria strain were slightly below average in the winter of 1976–77.26 It had been much ado about nothing.