Only a few hours left until the kick-off of the FIFA World Cup in Brazil … A reader from Germany recently sent me a clipping from the May edition of Germanwings inflight magazine (read it online here). The article on page 36/37 has this Sankey diagram:
Interesting visualization, though not fully in line with the basic rules for Sankey diagrams. The width of the bands represents the number of times the world cup has been won. The main issue is that only eight of the participating countries have ever won the cup (Brazil, the pentacampeão won it 5 times, so far…). For most of the nations shown, the green stream or arrow thus stands for zero wins. Zero (nil) however is impossible to display in a Sankey diagram, if you want to maintain the basic rule of arrows being proportional in width to the quantity displayed by them.
Several approaches have been proposed for the “zero quantity flows” such as a thin dotted line, or a thin line with a label “no flow”, or a colourless line. In the above case the choice of the diagram type is – in my opinion – not the luckiest one. The main message is that all teams are dreaming of getting to Rio’s Maracanã stadium on July 13.