Casualties Graph

Today’s Raleigh News & Observer ran an article about increased casualties within the 82nd Airborne Division, which is based here in North Carolina. There was a graph showing casualties by year, with the 2007 total being incomplete. A reader objected to the incomplete year being shown next to the complete years, and editor Ted Vaden thoughtfully opened a Reader’s Corner blog item to discuss ways the paper might have done a better job with the visualization.

I made a suggestion and later found some data at icasualties.org (which doesn’t quite agree with the N&O data from the Associate Press) to use to try out a few ideas.

First, this was my suggested idea, with one set of bars for the partial years values and another set of bars for the full year values. Here I overlaid the two since one is a subset of the other. You can at least see that the partial year total is not indicative of the full year total.

casualties1.png

Next is the same thing with the bars side-by-side.

casualties2.png

Another commenter suggested a view by month, which is revealing in showing clumps of dangerous periods for this division. The graph still has the problem that the bar for the final partial month carries the same weight as the other months. And the graph is showing a lot of data just to support a newspaper story.

casualties3.png

Given the sparseness of the data, I tried clumping the data into trimesters of 4 months each. Not bad but a trimester is not a common year division, adding a little work to decipher the date axis.

casualties4.png

Another idea is to look at average casualties per month for each year, but this has a more subtle partial data issue since 2007 has fewer values to average and so is less representative of the year. This is really equivalent to projecting the partial 2007 values for the full year, which the editor intentionally avoided.

casualties5.png

Finally, here’s a more scientific view, showing the monthly values with a trend line (spline smoother) overlaid.

casualties6.png

Thanks, Steve, for pointing me to this issue.