You can add reference lines to most Minitab graphs. The reference line on this bar chart of monthly sales represents sales quotas.
Reference lines are displayed behind data displays and may be difficult to see with some graphs, such as histograms. To create a reference line that sits in front of the graph's data display, use a calculated line instead. Go to Calculated lines.
You must use the scale units on the graph to position the reference lines. For example, if the y-scale has been transformed so that the tick marks are displayed in transformed units, you must enter the reference line position in the transformed units.
You can add reference lines when you create a graph.
You can add reference lines to an existing graph.
After you add a reference line, you can change its color, size, and type.
By default, the reference line includes a label on the high side of the graph.
Click and drag to move a label.
Rotate the label, for example to make adjacent labels easier to read.