RAND released a new report on Estimating Terrorism Risk recently, the latest academic contribution to one of the most difficult problems in homeland security: how do you assess terror-related threats and vulnerabilities. Historical analysis is likely to be of limited relevance, and terrorists adapt rapidly to changes in our protective measures, which makes probabilistic models (like those used for hurricane forecasting) problematic. It’s possible to model the criticality of key assets with some degree of accuracy, but only if you can account for the rippling effects of attacks on key systems and infrastructures.
The RAND report doesn’t attempt to solve all of these challenges, but it does look at risk estimation in the context of the DHS Urban Area Security Initiative (UASI) program and attempts to define a baseline for how cities should be funded in the program – an issue that has been controversial in the last two years, with many “second-tier” threat cities complaining about being left off the list.
The authors of the report seem to lean in favor of ‘event-based modeling’ as a preferred means of modeling terrorism risk, defined as:
Event-based models are built upon relatively detailed analysis of consequences from specific attack scenarios. These models include sensitivity analysis for important parameters that affect consequences. They may include components to model multiple types of events and multiple targets. They may also include modules that translate expert judgments of likelihood or consequences.
Their recommendations at the end of the report:
1. DHS should consistently define terrorism risk in terms of expected annual consequences.
2. DHS should seek robust risk estimators that account for uncertainty about terrorism risk and variance in citizen values.
3. DHS should develop event-based models of terrorism risk, like that used by RAND and RMS.
4. Until reliable event-based models are constructed, density-weighted population should be preferred over population as a simple risk indicator.
5. DHS should fund research to bridge the gap between terrorism risk assessment and resource allocation policies that are cost effective.