Conditions during disasters are highly unpredictable and the work demands generated by the disaster are highly dynamic. Therefore, there inevitably exists delay in information acquisition and response, as well as a difference between actual and
perceived data. For instance, during the response to Hurricane Katrina, newspapers reported that the there was difficulty in estimating the exact death toll and economic damage because of consecutive breaches of levees and the resulting flooding. Figure 7 shows an estimated death toll during hurricane Katrina. Because of lack of data availability of actual timings of casualties as they occurred, it is not possible to compare between actual and perceived lives lost. However, judging from several reports, it is certain that there was a delay in getting information after events happened, so that the first responders had to work with perceived data that differed significantly from actual data.