Mis-scaled bar chart


Here is a good example of a mis-scaled bar chart – it is from a recent Raconteur infographic called “Top 10 trusted countries for outsourcing legal work”Legal

Each bar (rendered in false 3D) seems to have a little handle on the end in the form of two lines perpendicular to one another.  It is not immediately clear whether the cross formed by this handle is encoding the data value or instead some other position on the end of the main bar.

Some of these handles are obscured by the data values that overlay them, and in the case of Scotland and to a lesser extent the US, the data value impinges upon the bar itself.  This breaks the sensible rule by William S Cleveland in his 1985 classic “The Elements of Graphing Data” that states “Do not allow data labels in the data region to interfere with the quantitative data or to clutter the graph”.

On comparison of the bar lengths with the stated values, it is obvious that there is no direct correspondence between the position of the handle or the length of a bar for each country and the value it encodes.  I replotted the data points in Excel in the chart below.


It is clear that the proportionality of bar length breaks down for the countries below Scotland, and the length of the bars for Eastern Europe, Asia and Philippines are considerably longer in the infographic than they should be.

One further comment – India and Philippines are countries within the continent of Asia and Eastern Europe is not a single country and as a region it is not well defined.

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