A proper Venn diagram depicts every combination of intersections. Rejiggering the layout won’t help. Every four-circle drawing suffers the same flaw. To see why, start with a single circle and ...

The man who invented the elegant overlapping circle diagrams would have been 180 today. Infographic: Which Flu Strain Is Most Likely To Bring The Apocalypse? H1N1? Bird flu? Swine flu? Confused?