Development of the multiregional inoperability input-output model (MRIIM) for spatial explicitness in preparedness of interdependent regions



Any given region in the US is a complex, interconnected, and interdependent economic system of systems that includes multiple stakeholders, spans multiple sub-regions, and produces a very large number of commodities and services. This paper provides a holistic, methodological framework with which to model the multisectoral and multiregional economic interdependencies inherent in such a large-scale and complex system, factors essential to making strategic preparedness decisions. The framework we present extends the Inoperability Input-Output Model (IIM) [Santos and Haimes, 2004], a model which has been developed to study these large-scale systems and which has been deployed in various studies. The basic IIM yields only average estimates across geography, and thus may provide insufficient information with which to make decisions about preparedness allocation within and across regions. Such average estimates may lead planners and policy makers to overlook geographically concentrated risks and significant cross-regional interdependencies, which are critical in evaluating strategic preparedness options. This paper extends the IIM to model the multiregional interdependencies among the various regions in the US by introducing and developing the Multiregional IIM (MRIIM) and by presenting the spatially explicit concepts of intraregional and multiregional interdependency matrices, A* and T*, respectively. The MRIIM possesses important properties that are derived from the databases that support the model and from the construction of the model itself. These properties guarantee unique solutions when studying the cascade of perturbation across regions and guarantee convergence when computational methods are applied. These properties also lead to a notion of resilience that is gained from cross-regional interdependencies. The major contribution of this paper is to demonstrate the importance of spatial explicitness in interdependency analysis through an example case study. © 2009 Wiley Periodicals, Inc. Syst Eng