By: John Boonstra on December 10, 2008 Chris Blattman’s ever-interesting blog yesterday featured this chart (from Columbia University statistician and social scientist Andrew Gelman), tracking how long it took for various conflicts — some with peacekeeping missions, some without — to return (or not return) to conflict: The information on the graph is a bit hard to take in right away, but study it for a little while, and the implication is clear: conflicts in which peacekeeping missions operated have had a much lower rate of returning to war; and when they do, they usually take longer to reignite. In analyzing these data, Chris plugs the new book by Page Fortna, Does Peacekeeping Work?, from which this chart is drawn. One of the best things about Page’s book is that she tries to investigate the (obvious) selection problem that could be driving the result: namely peacekeeping missions tackling the easiest conflicts. It’s difficult to measure, but her evidence actually points in the opposite direction: peacekeepers pick the tougher cases. If anything, we may be underestimating the effect of peacekeeping. Underestimating the effect that peacekeepers have on conflict-riven societies is unfortunately not something new, but this graph quite literally shows why such underappreciation is both unwarranted and contrary to fact.