Attractive, interactive graphic challenges lazy readers
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Confuse, confuses, confused, confusing

Via Twitter, @Stoltzmaniac sent me this chart, from the Economist (link to article):


There is simply too much going on on the right side of the chart. The designer seems not to be able to decide which metric is more important, the cumulative growth rate of vehicles in use from 2005 to 2014, or the vehicles per 1,000 people in 2014. So both set of numbers are placed on the chart, regrettably in close proximity.

In the meantime, the other components of the chart, such as the gridlines and the red line indicating 2005 = 100 are only relevant to the cumulative vehicle growth metric. Perhaps noticing the imbalance, the designer then paints the other data series in rainbow-colored boxes, and prints the label for this data series in a big white box. This decision tilts the chart towards the vehicle per capita metric, as our eyes now cannot help but stare at the white box.


There are really three trends: the growth in population, the growth in vehicles, and the resultant growth in vehicle per capita. They are all be accommodated in a small-multiples setting, as follows:


There are some curious angular trends revealed here. The German population somehow dipped into negative territory around 2007-8 but since then has turned around. Nigeria's vehicle growth declined sharply after 2006 so that the density of vehicles has stabilized.



Ted Max

The small multiples version is much improved. Yay! But am I the only person who still finds the graph a little baffling?

I would think that the car icon combined with the people icon would be cars per capita but instead it's just population? The accompanying text suggests that Nigeria "stabilized" after 2006, but the pink line (presumably showing per capita, I guess?) marches steadily upward throughout the time period. So I don't fully understand what "stabilized" means in this context.

This is a great improvement, but I'd personably just need another revision pass before I'd find it "clear." Am I alone in that?


TM: The people inside the car icon is indeed cars per capita. The one thing I did that confuses you is to switch the terminology to "density of vehicles" by which I mean "vehicles per capita." The gray line has stabilized for Nigeria: the growth of cars roughly equals the growth of people. I like to vary my word choice but in this case, it may be overdone.



Pink line is population (people icon)
Purple line is vehicles (car icon)
Dark line is vehicles per (car with people icon)

Ted Max

@jlbriggs: Okay, that makes sense, and fits what I'd have expected, as I mentioned. I still feel like I'm misinterpreting something based on the written analysis. Germany's slip into negative population growth is almost impossible to see at this resolution and doesn't seem to be happening around 2007-08 as far as I can tell.

Oh well, like I said, this is a much improved graph but it in combination with the accompanying text was still a bit confusing to me, and I'm no dummy. I wonder if it'd be better to toss out the pink line entirely. There's nothing of interest there, really.

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