Among the great resources at PerceptualEdge, consultant Stephen Few offers some very good discussions of individual data visualization problems, and proposes solutions for each of them. This isn’t a comprehensive treatise, but his commentary on individual cases is highly educational in itself.
Here’s a sample of a poorly done chart. Stephen rightly points out two major issues that make this misleading: a non-zero baseline, and discontinuous time frame on the X axis. I would probably add that the side-by-side column format makes aggregate comparisons of the two data series hard to digest.
Now here is Steve’s redesign of the chart. The problems identified have all been fixed in an elegant and highly functional chart. My only *small* nit with the reworked version is that the years only show up on the bottom-most chart of the three, forcing the viewer to scan down to the bottom of a long graphic in order to understand the time scale of data points at the top.
For numerous additional examples of Stephen’s great work and sound commentary, check out Stephen’s Examples page here.