Correlation vs Causation Interactive Widget

Perfect correlation, zero causation

Two variables can move together in lockstep — r = ±1.0 — yet have nothing to do with each other. Drag the slider to explore how correlation strength changes while the causal story stays fixed.

Scatterplot
r = 0.00
Drag slider to adjust correlation
No linear relationship
Correlation coefficient
−1.0 0.0 +1.0
r value
0.00
Causation
Zero

Ice cream sales and drowning deaths have strong positive correlation every summer — yet buying ice cream doesn't cause drowning. This is pure coincidence driven by a hidden variable: warm weather. Both variables rise independently when temperature climbs. The exam loves this trap because the numbers look convincing, but the causal story is fiction. Always ask: what else could explain this pattern?

Know This
r measures strength and direction of linear association, ranging from −1 to +1, but correlation never proves causation — watch for coincidence and common causes.