Before I started playing Guess the Correlation, I didn’t expect to spend an hour of my Easter weekend obsessing over an 8-bit video game, much less one based on something that many scientists do every day. I also didn’t expect to be hypnotized by graph after graph of black dots, trying to accurately gauge the patterns they concealed, in exchange for points and a place on a leaderboard. And I definitely didn’t expect to have fun doing it.
Guess the Correlation is the brainchild of Omar Wagih, a graduate student at the European Bioinformatics Institute, and nefarious devourer of the thing I once called “my free time.” On paper, it sounds incredibly boring. In practice, it is inexplicably addictive. Try it.
Players see a stream of scatter plots—common graphs that visualize the relationship between two things, whether temperature and ice-cream sales, or body weight and heart disease risk, or number of time spent on this infernal game and number of friends you have. Your job is to eyeball the plots and estimate a number called R, which measures how correlated the two things are. In the game, R can range from 0 (no correlation at all) to 1 (a perfect positive correlation).
Scientists do this all the time, making judgments about correlations by looking at scatter plots. It’s deceptively hard, which I discover as I play. A strong correlation, say where R is higher than 0.8, is obvious enough because the dots line up in a clean slash. Likewise, a weak correlation, where R is lower than 0.2, looks like the target sheet of a blind shooter. But there’s a large middle ground where my estimates are often hilariously off—which is why Wagih created the game in the first place.