The choice of a risks analysis method is a delicate stage in the path to ensuring the success of a risk study. The selected method must be adapted in any event to the problem arising and the study must remain in reasonable proportions with the size of the system or the installation and the nature of the risks suspected a priori. The choice of a risks analysis method can be guided by the examination of the six following criteria: motivation of the participants in the study, type of results requested, nature of information available, characteristic of the problem to be analyzed, perception of the risks, and experience of the team.