Data Smoothing: Loess: The Plots Tab

Data Smoothing: Loess

The Plots Tab

You can use the Plots tab (Figure 18.4) to create plots that graphically display results of the Loess analysis. The raw residuals are computed as $y - \hat{y}$ , where $\hat{y}$ indicates the variable containing 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 a smoother.

Confidence limits for means: specifies whether to add 95% upper and lower confidence 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.

Smoothing criterion vs. Smoothing parameter

creates a scatter plot of the smoothing criterion (for example, AICC) versus the smoothing parameter value for all smoothing parameter values examined in the selection process. The value that minimizes the criterion is indicated by a star-shaped marker.

Note: Stat 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.

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