Using Common, Separate or Difference Scaling

To scale the non-reference axis of graphs that contain a reference axis, select Goto  ®  Display mode.

The following options are provided:

  • Common scaling mode
  • Separate scaling mode
  • Difference scaling mode

These scaling modes are important when you are displaying more than one curve in the graph.

If you have only a single curve in the graph, these options have no effect. If your data has no reference axis, the options in this menu are not usable.

The scaling modes described here only apply to the non-reference axis. If this axis is the vertical axis of the graph, then the scaling mode you choose appears vertically on the right and left sides. If the non-reference axis is the horizontal axis, then the scaling mode appears horizontally on the top and bottom sides.

In the following description, it is assumed that the non-reference axis is the vertical axis.

The following sections describe these options.

Common Scaling Mode

This scaling mode scales both vertical axes of the graph the same. For multiple curves, an interval is found containing the lowest and highest point in all the curves. This is the interval used on both sides of the graph.

Visually, this process can have a flattening effect on most if not all of the curves. This is because the range of y-values for the graph as a whole is greater than or at least the same as the range for an individual curve.

The figure in the Overview shows a statistical graph with common scaling. Compare this with the following figure, which shows the same curves with separate scaling.

Note that SAP Statistics performs common scaling without regard to the units attached to curve values. Using Common scaling mode to display curves measured in different units (for example, in American dollars and German marks) is not a sensible option.

Separate Scaling Mode

Separate scaling only applies to graphs containing two curves. In this case, the scale range for each curve appears on either the right or left side of the graph.

The following figure shows an example of Separate scaling mode.

Difference Scaling Mode

Difference scaling is exactly the same as common scaling, except that scale values are based at zero. Each curve is re-scaled by finding the lowest value for the curve (on the non-reference axis) and subtracting it from all other values (for that curve).

A scale range sufficient to show all the curves based at zero is then displayed on both sides of the graph.

As is true with common scaling, difference scaling should only be used with curves all measured in the same units.