Homeland Security Watch

News and analysis of critical issues in homeland security

December 8, 2005

RAND report on estimating terror risk

Filed under: Infrastructure Protection,Risk Assessment — by Christian Beckner on December 8, 2005

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.

The entire report is worth a read. And this report out of Switzerland from 2004 is also a good primer on the issue.

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1 Comment


Pingback by Homeland Security Watch » Blog Archive » Local reactions to the UASI grants

January 4, 2006 @ 9:00 am

[…] On a final note, I’d like to recommend again a RAND report entitled “Estimating Terror Risk” that I highlighted in a post about a month ago. The report focuses precisely on the UASI grant program in its analysis, and the data in it might very well have been the basis for some of the risk prioritization decisions made by Sec. Chertoff yesterday – although there are clear discrepancies between their rankings of metropolitan areas and the Department’s list (e.g. San Diego is in the middle of the pack). It’s a good contextual read for people who are trying to understand the decisions made yesterday. […]

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