Statistics Dictionary

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Residual Plot

A residual plot is a graph that shows the residuals on the vertical axis and the independent variable on the horizontal axis. If the points in a residual plot are randomly dispersed around the horizontal axis, a linear regression model is appropriate for the data; otherwise, a nonlinear model is more appropriate.

Below, the residual plots show three typical patterns. The first plot shows a random pattern, indicating a good fit for a linear model.

Random pattern

The other plot patterns are non-random (U-shaped and inverted U), suggesting a better fit for a nonlinear model.

Non-random: U-shaped curve

Non-random: Inverted U

See also:   AP Statistics Tutorial: Residuals, Outliers, and Influential Points