  In this paper we present our ideas for conducting a cost benefit analysis by
using three different methods: scenario analysis, decision trees and
simulation. Then we introduce our case study and examine these methods in a
real world situation. We show how these tools can be used and what the results
are for each of them. Our aim is to conduct a comparison of these different
probabilistic methods of estimating costs for port security risk assessment
studies. Methodologically, we are trying to understand the limits of all the
tools mentioned above by focusing on rare events.
