Trainers & Games
Guess the Correlation
A scatter plot flashes up, you guess its correlation. A fast, addictive way to train the single most useful stat instinct.
Guess the Correlation
A cloud of points appears. Your job: eyeball how correlated they are and set the slider from −1 to +1. Guess within 0.10 and it counts toward your streak. The tighter your eye, the higher your score.
Correlation runs from −1 to +1 and measures how tightly two things move together: +1 is a perfect straight line up, 0 is a shapeless cloud, −1 is a perfect line down. Training your eye to read a scatter builds the intuition behind diversification, pairs trading and regression, where the whole game is knowing how much one series really tells you about another.
Learn how it works
Five worked examples. Read a couple before you dive in, try to answer first, then reveal the solution.
Near zero, the shapeless blob
The 50 dots form a roughly round, shapeless cloud, no tilt, points scattered evenly in all directions. What correlation would you guess?
Show solution
Guess about 0. The two clues to read are direction (which way the cloud leans) and tightness (how close it hugs a line). Here there's no lean and no line at all, knowing a point's x tells you nothing about its y. A circular, blob-like scatter is the picture of zero correlation.
Weak positive, a faint tilt
The cloud is still wide and fuzzy, but you can just barely see it leaning upward, higher x dots sit a touch higher on average. What's your guess?
Show solution
Guess around +0.3. The lean is upward, so the sign is positive. But the cloud is still fat and messy, so the strength is small. A faint, easy-to-miss uphill tilt in an otherwise broad scatter is the classic look of a weak positive correlation.
Strong positive, a clear band
The dots form a distinct upward-sloping band, clearly rising left to right, with only moderate scatter around the trend. What's your guess?
Show solution
Guess about +0.7. Direction is clearly up and the points now hug an upward line reasonably tightly, though there's still visible spread. A definite rising band that you'd confidently call a trend, but not a perfect line, is the signature of a strong positive correlation.
Very strong positive, almost a line
The 50 dots sit in a thin, tight ribbon rising steeply from bottom-left to top-right, barely any scatter. What's your guess?
Show solution
Guess around +0.95. When the cloud collapses into a near-straight line and knowing x almost pins down y, you're near the top of the scale. The tighter to a perfect line, the closer to +1. A thin rising ribbon like this is a very strong positive correlation.
Strong negative, a downward band
The band is clear and moderately tight, but it slopes the other way, falling from top-left down to bottom-right. What's your guess?
Show solution
Guess about −0.6. The tightness (moderate) sets the size, and the downward direction makes the sign negative. High x tends to go with low y. Any time the band clearly slopes downhill, put a minus sign on your guess, that's a strong negative correlation.
What you'll learn
An instant, gut-level feel for what different correlation coefficients actually look like, the intuition behind diversification, pairs trading and regression.