#percents

Y-axis at zero, please: I almost didn’t notice this but it’s the biggest problem with this graph and many others. See how the iOS bars are generally taking up a little more space than the Android bars? Makes you think iOS has a slightly bigger market share, huh? No, not at all. The Y-axis here starts ridiculously at 75%, actually Android has close to 85% market share. This is confusing and extremely misleading, whether it was done intentionally or not I have no idea

Change over time: When your x-axis is time, you probably want to be showing change over time, huh? But there’s very little change here. That’s not a problem per se, but as a person who works with data and makes visualizations, I generally produce simple versions of a bunch of graphs, then pick the best ones and make them clear and pretty. This would not make it into my final presentation.

Percents vs values: I feel like this is going to be a recurring topic. Percents are not the solution to every data problem. Percents are not always the best way to show what’s going on. Here, I’d be very interested in the total size of the worldwide smartphone OS market. Even if the percents for Android and iOS are about the same, are they still both adding customers? It’s a really important business question as well. If the market is increasing then to increase your share you need to capture new users. If the market is steady or shrinking, then you need to focus on converting users of the other platform. That’s an actionable insight that this graph could be providing but isn’t.