Bar vs. Line Chart – Part 1
How much data can you cram into one bar chart? The bar chart below, taken from GE’s 2006 Annual Report, attempts seven; six different business segments and the total for all segments. The only bar that is relatively effective is segment F, Industrial. Other than Industrial, I can see that the total revenue rises from $108 Billion in 2002 to $159 Billion in 2006. In general, I find it much easier to see trending over time by using a line graph versus a bar chart. As soon as you add more than one object to a bar chart with time across the x-axis, the graph becomes worthless.
Here is why I think this bar chart is ineffective:
¨ There are no labels on the y-axis for reference
¨ It takes entirely too long to cross reference a letter to business segment
¨ It is nearly impossible to differentiate scale after the first segment
¨ It’s deceptive because a segment may appear higher in subsequent years, only due to the lower segment increasing.
¨ The chart has too much unutilized (white) space in key areas
I have added two Excel graphs that I believe are much more effective. The only downside is that they use a bit more real estate. But, I welcome the tradeoff. The only difference between the two Excel charts is one is more horizontal and the other vertical. I prefer the one that is horizontal because I think it’s easier to view left to right.
The benefit to using the Excel version is each line graph is highly effective. Within seconds, I can see the trend of each business segment as well as the total trend for GE over the five-year period. If I were to use a tool that has a selection option, where the chart changes as a different segment is selected, I would be no better off. The problem is there can be no comparison when you only see one segment at a time. Edward Tufte popularized the term, small multiples, to represent a series of small similar pictures, making a point through repetition. See the examples and make your own conclusions.
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October 22nd, 2007 at 9:27 am
Tony
I love annual reports, they are the best source for bad charts.
There are only seven charts. Perhaps you could design a single row panel.
October 22nd, 2007 at 1:02 pm
I looked at some of the top annual reports and the data vis was terrible. I was going to try not to use a thumbnail in my post so the layout was key to fitting in wordpress. Ends up I used a thumbnail version… I may have another post as Part 2 that contains a sparklines version where I may try a row panel . Thanks for the comment!
October 29th, 2007 at 11:16 am
[...] the first part to this series, I revealed an alternative to the stacked bar chart that GE used in their 2006 [...]
November 5th, 2007 at 10:37 am
[...] 1) Bar vs. Line Chart Part 1 – Small multiples Line graph [...]