The analysis of historical information to determine levels of risk based on past experiences. The benefits of this technique are the identification of dynamic aspects involved in vulnerability and providing the criteria to assign relative weights to different dimensions of vulnerability in risk assessment exercises. The limitations to the approach are the reliance on historical disaster databases and the requirement for refinement, maintenance and systematic feeding of disaster data sets. In addition, statistics on previous disasters impact can be unreliable and rarely cover socio-economic aspects of the disaster; data on vulnerability is likely to be restricted to physical vulnerability, and reliance on historical assessment alone can create a false expectation of preparedness if hazards, which may not have previously occurred in the area of analysis have not been considered. (UNDAP, Techniques Used in Risk Asmt., 2008)