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?