Here’s a terrific post at the Forbes.com blog by Naomi Robbins, using a graph makeover to show that great graphs require thought; they don’t just happen.
I loved Naomi’s advice, but I saw room for additional improvement. As an educational exercise to help you build your data visualization muscles, I offer below my suggestions.
First, here is the original graph, used with the permisson of information designer Beth Najberg of Beginnings Design.
Naomi very smartly advises that the first step is to determine what point am I trying to make?
In this case, the graph-maker was trying to convey that the cost of insurance for the oldest persons was 4.4 times the cost for the youngest persons. The rule-of-thumb in the industry is the highest cost insurance should not be more than three times the lowest cost (the base rate).
Was that point clear in the original graph? Here is Naomi’s makeover:
This makeover demonstrates a few smart principles
1. First, clarify the point you’re trying to make. Naomi does this in the graph title.
2. Emphasize that point where the price is three times the base rate. It’s challenging for a casual reader to find that point themselves. Naomi adds a leader line to emphasize that value.
3. Use a bar graph instead of a line graph. In general, people perceive a line graph to mean something changing over time, like stock quotes or a president’s approval rating. But when all the measures come from the same time period, a bar graph communicates that more clearly.
Naomi’s graph is a big improvement. Still, there is even more you can do. Here’s my additional revisions:
Let me explain my additional revisions:
1. Subdue the color of the bars. Dark colors attract attention, but the size of all the bars is not the focus of this slide; the difference between the first and last bars is the focus. So use a lighter color.
2. Divide the bars into discrete blocks. It’s easier to see that something is 4.4 times larger than something else when you use 4.4 blocks for the largest item. I did this by creating a stacked bar chart that adds up to the total value, but you could do the same thing by just drawing white lines intersecting the bars. I also modified the y-axis to increments of $70, to make the block sizes meaningful.
3. Bold the values of the top and bottom bars. This is where you want to draw the eye’s attention. Don’t make the reader guess where you want them to look; emphasize those points.
4. Use lines to join the top and bottom values. You want to explicitly guide the reader to compare the top and bottom values. Lines subtly direct the eye to follow that path and make those connections.
This graph could be improved further. Do you see other ways to make the message clear?
Great graphs don’t just happen. They require you to think through your main message, choose graphs that communicate the message instantly and use graphic design techniques to highlight what’s important and draw the reader’s eye through the graph.
About the author: Bruce Gabrielle is author of Speaking PowerPoint: the New Language of Business, showing a 12-step method for creating clearer and more persuasive PowerPoint slides for boardroom presentations. Subscribe to this blog or join my LinkedIn group to get new posts sent to your inbox.