Like Hi Lo and Box graphs, Westinghouse graphs display multiple Y-values for each X-value. Westinghouse graphs, however, display two different Y-values in separate plots which share the same X axis but have different Y axes. Westinghouse graphs are typically used to display the mean and variance of the Y value over a range of X values.
You can adjust the appearance of the separate plots in the Westinghouse graph exactly as you would with the Line, Bar, Scatter, Histogram, and Box plots. The only major difference is the presence of two different Y axes. The Aux. Y Axis dialog box is used to customize the Y axis for the variance data. The controls for this auxiliary axis operate identically to those for the X, Y, and Z axes.
Figure 12.19: Westinghouse Graph