Wednesday’s post, Subterranean Veins of Europe, and its discussion of design choices distorting data reminded me of this map/graph sent to me by Barrett Lane last year. At first glance, this is a really neat and cleverly devised concept: the ridership numbers for each station on Boston’s Green Line are presented in the form of a stylised map of the lines, with vertical bars representing those numbers. It looks great, there’s some solid data behind the graphic, and the visual conceit is very appropriate.

However, there’s one major flaw that – for me – stops this graphic from being a total success. Barrett has used three different vertical scales for his graphs, which prevents rapid visual comparison between numbers (which one might say is the whole point of graphical presentation of data).

The same height represents 5,000 riders on the “B” and “C” branches, 4,000 riders on the “D” and “E” branches, and 20,000 on the main trunk line. The graphic would be far more effective if the bars for the trunk line stations towered above those of the branch lines, don’t you think?

Source: Barrett Lane