The following table describes the options in the Fitting menus.
Confid Curves Fit Displays or hides the confidence limits for the expected value (mean). This option is not available for the Fit Spline, Density Ellipse, Fit Each Value, and Fit Orthogonal fits and is dimmed on those menus.
Confid Curves Indiv Displays or hides the confidence limits for an individual predicted value. The confidence limits reflect variation in the error and variation in the parameter estimates. This option is not available for the Fit Mean, Fit Spline, Density Ellipse, Fit Each Value, and Fit Orthogonal fits and is dimmed on those menus.
Line Color Lets you select from a palette of colors for assigning a color to each fit.
Line of Fit Displays or hides the line of fit.
Line Style Lets you select from the palette of line styles for each fit.
Line Width Gives three line widths for the line of fit. The default line width is the thinnest line.
Report Turns the fit’s text report on and off.
Save Predicteds Creates a new column in the current data table called Predicted colname where colname is the name of the Y variable. This column includes the prediction formula and the computed sample predicted values. The prediction formula computes values automatically for rows that you add to the table. This option is not available for the Fit Each Value and Density Ellipse fits and is dimmed on those menus.
Note: You can use the Save Predicteds and Save Residuals commands for each fit. If you use these commands multiple times or with a grouping variable, it is best to rename the resulting columns in the data table to reflect each fit.
Save Residuals Creates a new column in the current data table called Residuals colname where colname is the name of the Y variable. Each value is the difference between the actual (observed) value and its predicted value. Unlike the Save Predicteds command, this command does not create a formula in the new column. This option is not available for the Fit Each Value and Density Ellipse fits and is dimmed on those menus.
Note: You can use the Save Predicteds and Save Residuals commands for each fit. If you use these commands multiple times or with a grouping variable, it is best to rename the resulting columns in the data table to reflect each fit.
Remove Fit Removes the fit from the graph and removes its text report.
Linear Fits, Polynomial Fits, and Fit Special, and Fit Robust Only:
Mean Confidence Limit Formula
Creates a new column in the data table containing a formula for the mean confidence intervals.
Indiv Confidence Limit Formula
Creates a new column in the data table containing a formula for the individual confidence intervals.
Confid Shaded Fit Draws the same curves as the Confid Curves Fit command and shades the area between the curves.
Confid Shaded Indiv Draws the same curves as the Confid Curves Indiv command and shades the area between the curves.
Plot Residuals Produces four diagnostic plots: residual by predicted, actual by predicted, residual by row, and a normal quantile plot of the residuals. See “Diagnostics Plots” on page 129.
Set Alpha Level Prompts you to enter the alpha level to compute and display confidence levels for line fits, polynomial fits, and special fits.
Smoothing Spline Fit and Local Smoother Only:
Save Coefficients Saves the spline coefficients as a new data table, with columns called X, A, B, C, and D. The X column gives the knot points. A, B, C, and D are the intercept, linear, quadratic, and cubic coefficients of the third-degree polynomial. These coefficients span from the corresponding value in the X column to the next highest value.
Bivariate Normal Ellipse Only:
Shaded Contour Shades the area inside the density ellipse.
Select Points Inside Selects the points inside the ellipse.
Select Points Outside Selects the points outside the ellipse.
Quantile Density Contours Only:
Kernel Control Displays a slider for each variable, where you can change the kernel standard deviation that defines the range of X and Y values for determining the density of contour lines.
5% Contours Shows or hides the 5% contour lines.
Contour Lines Shows or hides the contour lines.
Contour Fill Fills the areas between the contour lines.
Select Points by Density Selects points that fall in a user-specified quantile range.
Color by Density Quantile Colors the points according to density.
Save Density Quantile Creates a new column containing the density quantile each point is in.
Mesh Plot Is a three-dimensional plot of the density over a grid of the two analysis variables. See Figure 5.18.
Model Clustering Creates a new column in the current data table and fills it with cluster values.
Note: If you save the modal clustering values first and then save the density grid, the grid table also contains the cluster values. The cluster values are useful for coloring and marking points in plots.
Save Density Grid Saves the density estimates and the quantiles associated with them in a new data table. The grid data can be used to visualize the density in other ways, such as with the Scatterplot 3D or the Contour Plot platforms.
Figure 5.18 Example of a Mesh Plot