Dot size is used frequently, but I haven't seen many static visualizations that plot the series multiple times using cues (in this case, dot size and opacity) t

Dot size is used frequently, but I haven't seen many static visualizations that plot the series multiple times using cues (in this case, dot size and opacity) to indicate the data relationship. I see it all the time in animation form, though. It reminds me of the famous Minard chart of Napoleon's adventures [1], but doesn't draw the focus as completely to the time dimension as his does to the survivor dimension. I think you're right about the special nature of the third dimension in this case. I wonder what things other than time it'd work for. It feels like it'd work well for other things that are time-like -- results from different iterations of an experiment, for example. [1] http://en.wikipedia.org/wiki/Charles_Joseph_Minard#Work http://en.wikipedia.org/wiki/Charles_Joseph_Minard#Work