In general, most of what was prescribed made sense, and the questions the readings posed about data are important to keep in mind at all times. As with any set of rules, however, there is potential for over-restriction. Few dismisses the pie chart as a part-of-whole graph, claiming that the sizes of the different slices aren’t easily comparable, instead recommending the use of bar graphs. I disagree. First of all, a pie chart communicates the concept of part-of-whole wonderfully — the data literally adds up to make a whole! More importantly, pie chart slices are quite comparable to anyone who has read an analog clock. Amounts like a halves, thirds and quarters are instantly recognizable at a glance. Smaller proportions become less accurate, but serve to illustrate relative differences rather than allow accurate comparison. In a data set with many such small pieces that need to be compared a bar graph would me more appropriate, but the pie chart should not be dismissed as a tool outright.

For example, I try and stick to Tufte’s ideas when I write. By swapping “data” with “thesis” and “show” with “prove”  we get:

Above all else, prove the thesis.
Maximize the thesis-ink ratio.
Erase non-thesis-ink, within reason.
Erase redundant thesis-ink, within reason.
Revise and edit.
(By “thesis-ink” I mean any ink that works towards illustrating the thesis)

The field may be different, but the advice is the same: don’t clutter your work with anything that does not advance its purpose. Not only does his idea simply “fit” in other disciplines, but it remains good advice, and that is what is remarkable about Tufte.

Public domain work by Hal Jespersen (http://posix.com/CWmaps/)

Battle maps are something anyone who has read about war has seen. They illustrate the movements and interactions of different belligerents during armed conflicts. Details will vary from artist to artist, but all battle maps start with an actual geographic map of the battle location. On top of that, troop movements are represented. In this example, Hal Jespersen uses thick colored lines to represent various sub-orginizations of soldiers holding a position. Emanating from those are arrows, indicating advancement. Occasionally, an arrow with a dotted line is shown indicating retreat. Names are written near standing soldiers indicating the commanding officer’s name and serving to identify that group.

What I find fascinating about these maps is how they tell a story that can take place over days and weeks in a single static image. The entire story of rest, advancement, battle, defeat and retreat is told without varying time at all. Towards the bottom we can see, for example, that Toombs was holding the position behind the river, but was overrun by Burnside’s offensive across the bridge and forced to retreat. In response, A.P. Hill (arriving later) was sent to cover Toombs’s retreat and counter the advancing enemy. Burnside’s troops engage D.R. Jones’s forces to the North. The goal of the blue forces is to reach the city of Sharpsburg which is cocooned in thick red lines defending it.

Other stories are evident in the map as well. Several of sumner’s advances were forced to retreat, with D.H. Hill’s forces holding their ground. However, these forces were themselves forced to retreat and be reenforced, only stopping Sumner when they had pulled back considerably. This back and forth swing of domination of the battle field implies a very violent conflict, and the area is labeled “Bloody Lane”.

Battle maps are not perfect, and this example of their design is certainly no exception. In larger maps, it can become difficult to discern the chronology of events. In the example given, it is also impossible to tell the scale of the timeline in question. Did this battle take place in an hour? A day? A week? Anyone of them is a plausible answer, and the map does little to address the issue. The only hint we are given is the fact that A.P. Hill arrived in the “late afternoon”. The battle would have to have happened over the course of less than a day for that label to be meaningful.

Like I said, I really like how the events “as they unfold” are depicted statically and rather effectively. Complex narratives can be extracted from the map easily, and the goals and ambitions of two warring groups are made plain to see.