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Residual-by-Predicted Plot
A residual-by-predicted plot is commonly used to diagnose nonlinearity or nonconstant error variance. It is also used to find outliers. A residual-by-predicted plot, as illustrated by the plot on the left in Figure 39.25, is a plot of residuals versus predicted response for each observation. See the "Predicted Values" and "Residuals" sections for a further explanation of the axis variables.
Figure 39.25: Residual-by-Predicted and Residual Normal QQ Plots
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