This article at 9to5 Mac talks about the number the apps available on each leading mobile platform. To put things in perspective, they show a chart:
What’s the problem here? The wrong chart type is being used.
- First, the x-coordinate data points aren’t evenly distributed. March 10 is nine months away from June 09, while March 11 is five months away from Oct 10. That relative time distance can’t be understood, visually, in a bar chart.
- What the chart is trying to communicate is relative rate of change, over particular periods of time. For that, a bar chart isn’t the most effective tool; a line chart is, since for any given span of time, a single vertical view provides the relative comparison, rather than four horizontal hops.
A line chart communicates the rate by which Android is catching up to Apple, more effectively.