1 dimension + 1 metric
This visualization allows us to follow a progressive increase as the value of each bar is cumulated. In other words, each bar represents the current value added to the value of previous bars. This means that the added value each month can be easily seen in the difference between the value of the current and past bars.
Progression of bars that appear constant signifies little increase in value, while steep inclines indicate that the value of the metric has increased dramatically from the previous period.
A simple example
Let’s say that the dimension is
time:monthly and the metric is the amount of facebook fans.
Try it with your own data on the Visualization Playground
Let's analyze a bit
In that case, the bar length represents the total size of the facebook community and the different between each month represents the amount of new fans. We can then identify the months in which community size increased significantly.
Was your Facebook post content different during the former period? Were you more active online?