Data Visualization – Don’t Overcomplicate Charts & Graphs
One blog that I visit regularly deals with creating better PowerPoint presentations and is written by Jan Schultink. I am in the data analysis and visualization business, but typically use presentation software to run meetings, webinars or communicate data analysis results. So, creating effective and powerful presentations is important so the hard work that goes into the analytics isn’t lost in the communication.
Below you will find the data visualizations that Jan showed on his site. I would agree that the second image is better at showing the difference versus the first one, but not by much. The probability of 1 in 76 is definitely more meaningful (puts it into context) than the 1.3% data point. What I have an issue with is that the area of both columns (2nd image below) is almost the same with the one on right being slightly larger. What makes the two columns represent different values is the number of spheres within each column. The one on the left contains 8,000 circles (I’m assuming because they are not very countable) while the one on the right has 76 circles.
Honestly, I’ve never created a data visualization like this to even know how to make this chart with so many spheres that are microscopic. My guess is that it could be done using Adobe Illustrator or similar software.
Risk of maternal death as a percentage:
Risk of maternal death as 1 in x number
[source]
Here’s where I think we can improve the visualization without losing effectiveness. In a fairly popular post that I did a while back, I suggested the best method for showing a single data point is the following image. I think that the 1 in 8,000 compared to 1 in 76 data points are powerful enough and take up very little space to convey the message. Another option would be to compare the two data points and only show the difference as a single metric. It would go something like this:
Illustration for showing a single data point:
So my question would be – which method do you think would be more effective in a presentation?
September 24th, 2009 at 8:41 am
To tell you the truth, I prefer Jan’s approach, subject to your issue with the size of each block of circles. His chart shows me instantly that there is a huge difference in risk of maternal death between developing and developed countries. The visual impact is strong, and the labels help the reader fill in the background of this impression.
Your single data value shows me a piece of text, which I first have to convert from a picture of the numerals into a feel for that number. I then have to read the explanation, determine that this presents some kind of ratio or multiplier, then finally begin to understand it. Not as quick or intuitive as Jan’s graphic.
September 25th, 2009 at 5:58 am
I agree with Jon on conveying impact.
Well 130 times would be a high number, but I can’t make out how big it is until I have something in front of my eyes.
Previous chart somehow makes it obvious with not only number, but size of circles that give a visual impact of risk comparison being small in developed countries as compared to big in developing countries.
September 25th, 2009 at 3:24 pm
Some good points Jon. I believe we agree that: 1) the first image is not really that effective conveying the message 2) My text doesn’t put the message into context to see the individual numbers and their magnitude. I think we also agree that there is an issue with the two columns not being the same size.
I feel my example takes it a step farther and puts some analysis on the individual numbers to take the reader where they may eventually want to go. I agree that the individual numbers are important and should be shown. If I was developing the presentation, I would forgo the graphic and show: 1 in 8000 versus 1 in 76 = 130 times greater risk. I would dress it up a bit, but you get the point.
September 25th, 2009 at 3:30 pm
Hi Parveen – welcome to the Support Analytics Blog and thank you for leaving a comment!
After further thought and input from you and Jon, I agree that the individual numbers are important to effectively communicate the full picture. I find it very difficult to see the small spheres and have no idea if there are 8000 of them. Honestly, at first glance, I didn’t even know there were dots in the left column. It looked like a texture that you can add to a chart.
I think showing the numbers: 1 in 8000 versus 1 in 76 = 130 times greater risk would be the way I would have gone. Thanks again!
September 25th, 2009 at 5:15 pm
By first image, do you mean the plain bar chart? Yes we agree. I found the second image rather effective despite the microscopic dots. Even lacking the ability to resolve the tiny orange dots, having one tiny red dot and a big arrow really hits you over the head. Adjusting the arrangement of dots in the two bars so each has a similar area would improve it.