摘要Disaster science and scholarship are forever expanding and there are increasing calls to base disaster risk reduction policies on the evidence produced by such work.Using examples and argument,this opinion piece examines the nature of evidence.It defines evidence-based practice and considers how it has developed and become important to disaster risk reduction.A definition of what constitutes evidence is difficult to achieve but it must be made in relation to whether the data and information col-lected can usefully be interpreted and employed to change things for the better.Case histories from past and present centuries show that evidence can sometimes be argued over endlessly.In other cases it is roundly ignored.In yet other instances,false conclusions derived from evidence can become evidence in their own right.Nevertheless,there are situations in disaster risk reduction in which evidence is sorely needed but is clearly lacking.The effectiveness of counter-terrorism measures is one such area.In conclusion,evidence is valuable,above all if there is willingness to use it to support policy formulation,especially in a simple,transparent manner.Subjective interpretation can never be entirely removed from the use of evidence,and evidence alone will not stimulate the policy formulators to improve their decision making.