Figure 8

Inter-event timing signatures. Color bars illustrate the results of a KS-test for exponential distribution of the inter-event times in time windows of $T=180$ days for thresholds equal to 1, 2, 4, 5, 7 and 10 casualties (see text for details). The bars indicate the center of those time windows for which the hypothesis of agreement of the distribution of inter-event times with an exponential distribution can be rejected at a 5% significance level (i.e., the datasets exhibits a non-trivial timing structure). The graph also shows the dynamics of the number of events per day in ‘IBC Baghdad’ (red) and ‘SIGACT Baghdad’ (blue). The vertical axis for the IBC dataset was mirrored for clarity purposes.