1.2.4-4 Consistent Orientation of Bars

In a related series of bar charts, a consistent orientation of the bars (vertical or horizontal) should be adopted.

Additional Information:
If bar length is used to represent time duration, then it might be more appropriate to orient the bars horizontally, in accord with the general convention of plotting time on the horizontal axis of a graph. Vertical bars can be used to display frequency counts or a large variety of other measured attributes.