quincunx
for {{name}}, one bean at a time
rows
bias
50% / 50%
balls: 0 · mean: —
Francis Galton called it a quincunx — from the Latin for the
five-dot pattern on a die — and used it in a lecture at the Royal
Institution on 27 February 1874 to demonstrate the normal
distribution emerging from independent binary choices. Each ball
falls the same way: at every peg, left or right with equal
probability. The bell curve at the bottom is not designed. It
arrives.
Galton didn't stop at fair coins. A quincunx with a weighted peg — a board tipped slightly, or pegs shaved so the ball favours one side — still produces a bell curve, just a binomial one shifted off centre. The rows control changes how many independent choices each bean makes before it lands; the bias slider changes the odds of each individual choice. The dashed line is always the theoretical curve for whatever row count and bias are currently set — the histogram is chasing a moving target now, not a fixed one.
keys: space drop · A auto · B burst · C clear · 1-6 row count · [ ] bias
Galton didn't stop at fair coins. A quincunx with a weighted peg — a board tipped slightly, or pegs shaved so the ball favours one side — still produces a bell curve, just a binomial one shifted off centre. The rows control changes how many independent choices each bean makes before it lands; the bias slider changes the odds of each individual choice. The dashed line is always the theoretical curve for whatever row count and bias are currently set — the histogram is chasing a moving target now, not a fixed one.
keys: space drop · A auto · B burst · C clear · 1-6 row count · [ ] bias