I agree completely with this Junk Charts entry, which presents two examples (from the Wall Street Journal on 9 Nov 2005) of bar graphs that become much much more readable when presented as line graphs. The trends are clearer, the comparisons are clearer, and the graphs themselves need much less explaining. Here’s the first graph (and its improvement):
And here’s the second:
My only (minor) comments are:
– First graph should be inflation-adjusted.
– Both graphs could cover a longer time span.
– Axis labels on second graph could be sparer (especially the x-axis, which could be labeled every 5 years).
– I’d think seriously about having the second graph go from 0 to 100% with shading for the three categories (as in Figure 10 on page 451 of this paper, which is one of my favorites, because we tell our story entirely through statistical graphics).
– The graphs could be black-and-white. I mean, color’s fine but b&w is nice because it reproduces in all media. The lines are so clearly separated in each case that no shading or dotting would be needed.
P.S. See here for a link to some really pretty graphs.