1. What are the different types of database?

There are four main types of database:

• Non-quantified accident databases report the nature of many accidents (fire, explosion, etc.), their causes (when identified) and their consequences (nature and extent of damage to the environment, property or people).

• Quantified "sector" databases report accident or dread event frequencies for each sector of activity, based on statistical analysis of experience feedback (number of accidents observed over an observation period T).

• Generic" quantified databases report frequencies of accidents or feared events from different sources, or based on values corrected by experts.

• Reliability databases provide failure rates for equipment required for process control and operation (temperature sensor, transfer...