Hiding Observations

Slicing

Slicing is a dynamic technique for subsetting your data based on a range of values for one variable. You can create a brush both to restrict the range of values in one plot and to select observations in all plots. You can slice dynamically to explore relationships in more than two dimensions.

Follow these steps to see how GPA is related to the two SAT scores.

Drag a rectangle with the mouse in the scatter plot of SATM versus GPA.

This selects the observations within the rectangle and creates a rectangular brush.

Move the brush by dragging with the mouse inside the brush.

Observations that are selected by the brush become visible in both scatter plots. The second plot shows the conditional distribution of the data as restricted by the position of the brush in the first plot.

Figure 9.15: Brushing Invisible Observations

Drag the corners of the brush to make it tall and thin.

This restricts selected observations to a narrow range of values for GPA.

Move the brush to the left and right.

The scatter plot of SATM versus SATV in Figure 9.16 shows the joint distribution of the two SAT scores when GPA is near 4.0. By sliding the brush, you can see whether the distributions change significantly as GPA increases or decreases.

Figure 9.16: Slicing Observations

Use the scatter plot pop-up menu to make observations visible again.

[menu]
Figure 9.17: Scatter Plot Pop-up Menu

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