In this episode from the Cautionary Tales podcast, Harford teams up with actor Helena Bonham Carter, a distant relative of Florence Nightingale, to tell the story of how the ‘“Lady with the Lamp” revolutionized public health with a pie chart. Nightingale was a statistician as well as a nurse, and it was her use of data graphics that led hospitals to introduce hygiene measures that we now take for granted. Her charts convinced the establishment that deaths due to filth and poor sanitation could be averted, saving countless lives. But did Nightingale also open Pandora’s Box by showing that graphs persuade, whether or not they depict reality?