A scatterplot flickers into view and starts fading, estimate its correlation, set how wide a band you'll wager, and call it before it's gone.
Each round you see a scatter of points and must judge its correlation (r) from roughly -1 to +1. Slide your guess to the center of a band, choose how tight that band is, stake some coins, and CALL before the plot fades. If the true r lands inside your band you win; tighter bands and closer centers pay more.
Eyeball-r is a correlation-estimation game that sharpens your statistical intuition for scatterplots.
Judging a scatter's correlation coefficient by eye is estimation of Pearson's r, the standard measure of linear association running from −1 to +1.
Choosing a confidence band rather than a point value is the original scoring.
Eyeballing r is notoriously unreliable, and in a specific direction: people overestimate weak correlations and underestimate strong ones, and the impression depends on the axis scaling as much as on the data. Being asked for a range rather than a number is the honest way to be graded on it.
Eyeball-r is a correlation-estimation betting game that sharpens your statistical intuition for scatterplots. It's an original free browser game built for PlayPendium.