The Truthful Art: Data, Charts, and Maps for Communication

9. Seeing Relationships

Guy: “I used to think correlation implied causation. Then I took a statistics class. Now I don’t.”

Girl: “Sounds like the class helped.”

Guy: “Well, maybe.”

—Dialogue in an XKCD.com cartoon: https://xkcd.com/552/

There are certain headlines that are impossible for any journalist to resist. I’ll give you one: “Eat More Chocolate, Become Smarter!” You may think that I’m joking, but here’s a real 2012 headline from Reuters: “Eat chocolate, win the Nobel Prize?”

The story—written tongue-in-cheek, or so it seems—was based on a “study” by Dr. Franz H. Messerli, director of the Hypertension Program at New York City’s St. Luke’s-Roosevelt Hospital, published in the well-respected New England Journal of Medicine. Reuters wasn’t ...