Correlation Does Not Equal Causation! Two unrelated series of events can follow the same pattern and our human brains will work very hard to see a relationship, no matter how nonsensical. Vigen has a lot of fun with this, devoting a page and a graph to each silly pair:
Cheese consumption by Americans correlated at a whopping 94.7% with fatal bedsheet tangling accidents between 2000 and 2009.
Between 1980 and 2008, the pregnancy rate had a 90.9% correlation with the output of nuclear power plants.
But shark attacks and tornadoes had only a 77.4% correlation between 2002 and 2010.
And then there's the 99.5% correlation between computer science doctorates awarded 2003-2009 and comic book sales over the same period. Is that one spurious?
There is a serious side to this. Spurious correlations have led experts astray in the past, for example the Phillips curve in economics. But today, it has become easy to use huge digital databases and computing to find such patterns through “data dredging.” Vigen's Spurious Correlations highlights a new critical thinking skill we need to develop as everyone from politicians to businesses tries to convince us that an apparent relationship is proof. I was reminded of Proofiness by Charles Seife reviewed here a few years back.
Review by Carolyn Caywood, retired from VBPL