How to Read Bar Graphs and Cumulated Bar Graphs


The bars allow the comparison of a large number of different elements within the same dimension, sharing a common metric. Effective for showing a time evolution, that is to say where the dimension is time and each value of the dimension is a date.

Let's say you want to visualize your website's visits over time. Here, the dimension is time:monthly so each bar is a month and the metric is visits so each bar height is relative to the number of visits for this month. 2015-03-31 13-05-45

At a glance we can see that there’s seasonality in our database, with almost regular sinusoidal variation. At the same time, we can see that 2013 outperformed 2012. As we take a closer look, we see that our best months in both 2012 and 2013 are February, March and April. Moreover, we can quickly spot that 2013 outperformed with a gap consistent with other months. We can also note that September was consistently positive with significant audience peaks, as compared to appalling performance in August of both years.

So, the question that we need to answer at this point is - what does this mean for our business?

In order to play around some more with bar graphs you can head over to the Visualization Lair at .


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.

Let’s say that the dimension is time:monthly and the metric is the amount of Facebook fans. 2015-03-31 13-06-07In 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. The community size increased more significantly between June and July 2013 in comparison to July and August.

Here the questions we can answer are - Was your Facebook post content different during the former period? Were you more active online?

In order to play around some more with cumulated bar graphs you can head over to the Visualization Lair at .