Data Smoothing: Polynomial Regression

Plots Tab

You can use the Plots tab to create plots that graphically display results of the analysis. (See Figure 20.4.) The raw residuals are computed as $Y - \hat{Y}$, where $\hat{Y}$ indicates the variable that contains the predicted values of the response.

Creating a plot often adds one or more variables to the data table. The following plots are available:

Observed vs. Explanatory with smoother


creates a scatter plot of the X and Y variables, overlaid with the polynomial smoother.

Confidence limits for means


specifies whether to add 95% upper and lower confidence limits to the Observed vs. Explanatory plot.

Prediction limits for individuals


specifies whether to add 95% upper and lower individual prediction limits to the Observed vs. Explanatory plot.

Observed vs. Predicted


creates a scatter plot of the Y variable versus the predicted values.

Raw residuals vs. Predicted


creates a scatter plot of the residuals versus the predicted values.

Raw residuals vs. Explanatory


creates a scatter plot of the residuals versus the X variable.

Residual normal QQ


creates a normal Q-Q plot of the residuals.

Note: SAS/IML Studio adds a smoother to an existing scatter plot when both of the following conditions are satisfied:

  • The scatter plot is the active window when you select the analysis.

  • The scatter plot variables match the analysis variables.

Chapter 18: Data Smoothing: Loess, discusses how to display multiple smoothers in a single scatter plot, and how to remove smoothers from a scatter plot.