There are several types of graphs (such as bar charts, pie charts and the simple line graphs), but which is the best one to tell your story? Or do you think you can easily swap between one and another? Spoiler alert: you can, but shouldn’t!
In today’s post we are going to walk you through the different types of graphs and the rules of thumb regarding the effective use of each.
Let’s start with the pie chart, as this is the one we most often see abused. John recently saw a pie chart with 21 segments. Now to protect the identity of the author of this report, we’re not going to name and shame them, but it did originate on the New Zealand side of the Tasman Sea!
Pie charts are useful for showing proportions or the relative amounts when there is a large difference between the size of the various segments. They’re great for presenting a simple concept, ideally where one segment is much larger than any other. The rule of thumb is that there should be no more than six segments in your graph. If you have more than that, consider using a horizontal bar graph. To give greater emphasis on a particular segment, you can explode or pull it out from the others. It is often helpful to place the percentage amounts inside the segments and the labels outside each segment, to make quick comparison easier.
Horizontal bar charts are good for showing small differences between values. The bars should be sorted from longest to shortest to help demonstrate the relative sizes. It’s usually better to place the labels on one side and the percentage amounts on the other side.
Column charts, or vertical bar charts, are useful for illustrating trends. A stacked format where one bar slightly overlaps another, can be used to show two related data sets. While the labels need to be fairly narrow, it’s better to keep them horizontal so the reader doesn’t need to tilt the page sideways to read them.
Finally, line graphs are used to show trends for continuously changing variables, such as temperatures. They can simplify a large amount of data very effectively. The rule of thumb is to use only up to six lines on the one graph, otherwise it becomes overly complex.
So there you have it. Some fairly simple rules of thumb of which graph to use when. We know there are 101 other types of graphs, but we just wanted to focus on the key ones for this episode.
Well, you’ve heard our thoughts, now we would like to hear yours! Add a comment below this post and tell us about your experiences with using graphs effectively, or share your favourite horror story graph! We don’t want this to be just a one-way conversation – join in by sharing your thoughts and ideas with us!
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