Reference Lines

You can add a vertical and/or horizontal line to emphasize a specific value in your chart. For example, if your data are salaries that you want to compare to last year's, you can display a reference line that represents last year's average salary. You can also add a reference line from a specific equation.

How to Add a Horizontal or Vertical Reference Line

  1. From the menus choose:

    Options > X (Y) Axis Reference Line

    The Chart Editor creates the reference line near the center of the chart and opens the Properties window to the Reference Line tab.

  2. Use the Reference Line tab to specify a position for the reference line.
  3. If necessary, use the Lines tab to change the formatting for the reference line. See the topic Line Style for more information.
  4. Click Apply.

How to Add a Reference Line from an Equation

Note: Creating a reference line from an equation is available only for 2-D charts with two scale axes.

  1. From the menus choose:

    Options > Reference Line from Equation

    The Chart Editor creates a linear equation reference line with a slope of 1 and y-intercept of 0. The Chart Editor also opens the Properties window to the Reference Line tab.

  2. Use the Reference Line tab to modify the equation.
  3. If necessary, use the Lines tab to change the formatting for the reference line. See the topic Line Style for more information.
  4. Click Apply.

How to Edit a Reference Line

  1. Select the reference line.
  2. From the menus choose:

    Edit > Properties

  3. Axis reference lines only. Use the Reference Line tab to specify a position for the reference line. You can also drag and drop the reference line to a new location. Use the tab if you need to move it to a precise location.
  4. Equation reference lines only. Use the Reference Line tab to define the equation used to create the reference line.
  5. If necessary, use the Lines tab to change the formatting for the reference line. See the topic Line Style for more information.
  6. Click Apply.

How to Delete a Reference Line

  1. Select a reference line.
  2. Press Delete.

Using the Reference Line Tab

Scale Axis. Change the position of the reference line by entering a numeric value for a scale axis or choosing a common statistic from the Set to drop-down list. You cannot specify a value outside of the range of the displayed scale.

Category Axis. Change the position of the reference line by choosing a category for a categorical axis.

Custom Equation. Specify a custom equation for drawing the reference line. This option is available if you created the reference line by choosing Reference Line from Equation from the Options menu. It is also available for charts created by procedures that produce these lines (like Curve Estimation). For information about valid expressions, see Equation Syntax .

Attach label to line. Attach a label to the reference line for displaying the position of the line. The label displays a numeric value for scale axis reference lines, a category value for category axis reference lines, and an equation for reference lines from an equation.