Burden of Proof

In 1918, Frederick Hoffman, a senior statistician at Prudential Insurance, published a landmark report highlighting the large number of asthma-induced deaths among US coal miners. At the time, the medical community was hardly concerned about possible adverse health effects of working in coal mining – one of the leading industries at the time. The conventional wisdom was that coughing up dust particles was a healthy bodily reaction. Hoffman presented statistical evidence that miners were five times more likely to die of asthma than the rest of the working male population and that only one-fifth of miners were able to work past...