One Word Is Not a Description of a Scatterplot

You'll learnwhich variable goes on which axis and why that choice changes the line later, the four features a complete scatterplot description covers — form, direction, strength, unusual points — and why each feature on its own is shared by clouds that could hardly be more different.

Eight students report their weekly study hours and their exam scores, and the cloud they make rises. Saying so is the answer most students give, and it earns about a quarter of the credit. This page draws a second cloud that is also positive but far looser, a third built from a curve that a straight line still fits well, a pair of clusters that each rise while the two together fall, and finally the same eight students with the axes swapped, which moves the fitted line. Each picture takes away one shortcut. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · AXES · FORM · DIRECTION · STRENGTH · UNUSUAL POINTS · v2

Both clouds are positive; a curved one still fits a line at r = 0.925

Before you start

What you're looking at

Eight students' weekly study hours and exam scores, one dot per student — then three more clouds, each built to break one shortcut.

The question

What has to be said about a scatterplot before the description actually fits these data?

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