Math 1 · Unit 10 · Lesson 3 · part 3 of 5
The residual plot: random scatter or a pattern?
One residual tells you about one point.
The residual plot: random scatter or a pattern?
One residual tells you about one point. All of them together tell you whether a line was the right family. A residual plot puts the x values along the bottom and the residuals up and down, with a flat line at 0.
Here is the tuition data in the regression tool. The tool's own least squares line is very close to the suggested model. Tap a point, or use the button, to see its residual drawn as a vertical segment. The second grid below is the residual plot.
The tuition residuals bounce above and below 0 with no pattern: a line is a good model here.
Now Sno-Show Sno-cones: the average weekly temperature and the number of sno-cones sold that week. Find r, then check the residual plot.