Have you ever been asked to create some form of visualization for a presentation? You have heard about pie charts, bar charts, and line charts. But what chart type to use and when?
To know which visualization to use, you must first know what message you are trying to convey. Understanding what you are trying to say is as important as how you are going to showing it.
For example, you need to display the total revenue. Sounds straightforward and simple. The use of a text box along with the actual value will do the trick.
Next, you need to add in the origination’s target for revenue. You can incorporate that information in a couple of ways. Adding additional text and color to the number is one way. Another way would be to use a gauge. Both ways will help the audience understand how the actual compared to the target. Also, keep in mind if the document will be printed in color or black and white. If the information is being printing in black and white, adding icons to help illustrate the comparison of actual to target is essential. Using (X or √) or (↓ or ↑) or even (☺; or ☹) will provide useful information to the audience.
Now you are asked to include the previous period’s data. How do I represent both numbers? Do I show both values or percent change between the periods? Do I use a bar or pie chart?
Using the bar chart allows the audience to easily identify that the current month was better than the previous month.
A pie chart wouldn’t be the choice to use for this example. A pie chart is best suited for when you want to show a breakdown of components as they relate to a whole.
Another change, they want to show how revenue has been trending for the last 13 months. Both a line or bar chart could be used.
If the main message is how revenue has been trending, then the line chart would be the correct chart to use.
If how revenue has been trending and the actual values are equally important, then a bar chart would be the best way to provide that information.
Finally, the last change is in. They want to include the organization’s target along with trending for the last 13 months. The line chart can be used again, but instead of using a bar chart, the combo chart is a better choice.
Use the line chart if the trend is more important than the actual values.
Be careful when adding additional measures that have different scales. Having a secondary Y-Axis could cause misleading information.
Using the same Y-Axis for both the bar and line will in a combo chart provide the proper relationship between the two measures.
In conclusion, when preparing visualizations, make sure you ask these questions:
What needs to be presented? Why are these visualizations being created? How are the visualizations being distributed? Understanding the WHAT, WHY and HOW are critical in the right message being delivered.