It's one thing to calculate a correlation coefficient ($r$) using a computer. It's another thing entirely to spot it with your own eyes. This "stats hack" is about training your brain to ignore the noise and see the signal.
The Challenge: A scatterplot will appear below. Use the slider to guess the correlation coefficient. Try to get within 0.10 of the actual value!
Session Results
Here is how you performed against the machine.
Rounds
0
Mean Error (MAE)
0.00
Best Guess
Diff: 0.00
Bias
0.00
Round 1
Goal: ±0.10
0.00
-1.0
0.0
+1.0
Cheat Sheet: What to Look For
- The "Fat Pencil": If the points look like they could fit inside a fat pencil, the correlation is usually strong (around $0.8$ to $0.9$).
- The "Football": If the points form a shape like an American football (oval), it's often moderate (around $0.5$ to $0.7$).
- The "Cloud": If it looks like a circular cloud or a shapeless blob, $r$ is likely close to $0$.
- The Direction: Always check if it's going up (positive) or down (negative) before you guess!
