ABSTRACT
We have run experiments with 17 groups with three participants—to see how they assess hazards, probability and possibility to avoid dangers. We considered two scenarios taken from ISO 15998-2. We used a three-step process—each participant read the scenario and assesses consequence, probability of the event and the possibility of avoiding the hazard. Then they wrote down their rational for the assessments and adjusted. They then presented their rationales to the other two members and made final assessments.
We discuss the results: what rationale made participants change their assessments, and which parameters were changed? As in earlier experiments, risks are overestimated. We need to improve the way we describe hazardous scenarios so that we can get more realistic risk assessments.
There exist several guidelines for writing scenarios, and they are followed by ISO 15998-2 but this did not seem to help. We suggest some new guidelines for scenario description.
