Scatter Plots

Does more study time raise test scores? Does taller mean heavier? Each person hands you TWO numbers — hours studied and score, height and weight. On their own the numbers are lists; but plot each person as a single dot at (hours, score), and the cloud of dots reveals whether the two variables move together. A scatter plot turns two lists into one picture, and your eye — a world-class pattern-finder — reads the trend instantly.