Drag the slider to set a target r; the scatter is regenerated to match. Watch how r encodes direction (sign) and strength (how tightly the cloud hugs a line) — not the slope. r = Σ(x−x̄)(y−ȳ) ÷ √[Σ(x−x̄)²·Σ(y−ȳ)²].
x & y are unitless [0,1]. The same r can come with a steep or a gentle cloud — r measures tightness about a line, not the line's slope.
Actual computed r
Strong Positive
Try: set r near 0 with the slider — the cloud is shapeless. Now hit Curved (U): there is an obvious pattern, yet r stays near 0. r only detects linear association. Also slide from +0.9 to −0.9: the cloud flips direction but the tightness (strength) is the same — sign is direction, magnitude is strength.