Workspace Node: 2D Bag Plots - Advanced Tab

In the 2D Bag Plots workspace node dialog box, select the Advanced tab to display the following options.

Element Name Description
Variables Click this button to display a variable selection dialog box, in which you select the variable(s) to be plotted. When you select more than one variable, a sequence of graphs is produced (one for each of the variables). A list of the selected variables is displayed adjacent to the Variables button. If you select marked subsets, the method of categorization selected will apply to all bag plots.
Graph type

Select the type of bag plot to be plotted from the Graph type list. Click the type of the plot link listed below for a brief description of that type of graph.

Regular

Multiple

Double-Y

Ellipse Use the options in this group box to superimpose an ellipse on the data in the bag plot. You can display one of two types of ellipses (Normal or Range, see below), or leave it off (select Off).
Normal Select this option button to produce an ellipse based on the assumption that the two variables follow the bivariate normal distribution.

The orientation of the ellipse is determined by the sign of the linear correlation between the two variables (the longer axis of the ellipse is superimposed on the regression line).

The ellipse shows the prediction interval for a single new observation, given the parameter estimates for the bivariate distribution computed from the data, and the given N.

If the number of observations in the scatterplot is small, then the prediction interval may be very large, exceeding the area shown in the graph for the default scaling of the axes. Thus, in some cases (with small N) you may not see the prediction interval ellipse on the default graph (change the scaling to show larger intervals for the two variables in the plot). For additional information see, for example, Tracy, Young, and Mason (1992), or Montgomery 1996; see also the description of the prediction interval ellipse.

Range Select this option button to produce a fixed size ellipse such that the length of its horizontal and vertical projection onto the x- and y-axes (respectively) is equal to the mean ± (Range * I)/2 where the mean and range refer to the X or Y variable, and I is the current value of the coefficient field.
coefficient Specify the coefficient that controls the ellipses described above.
Mark Selected Subsets. Click this button to display the Specify Multiple Subsets dialog box, in which you can specify selection conditions that will subset (such as categorize) the cases in one plot.

For more information about this option, see Mark Selected Subsets.

Bag plot properties The options in this group box control the appearance of the bag plot.
Whisker type There are three options available on the drop-down list:

Off suppresses the display of the whiskers.

All whiskers connects all points that are outside of the bag and within the fence to an edge of the bag.

One per edge connects only the point furthest away from a respective edge of the bag.

Show points in bag Select this check box to display data points that fall within the bag.
Show outliers Select this check box to display the outliers, the data points that fall outside of the fence, with a unique point marker different than the point marker used for the raw data points.
Fence coeff The fence coefficient is the factor that is used to magnify the bag to create the fence.
Bag coeff The bag coefficient specifies the percentage of data points that the bag captures.
Options / C / W See Common Options.
OK Click this button to accept all the specifications made in the dialog box and to close it.

The results are placed in the Reporting Documents workspace node after running (updating) the project.