<p>Mortality data, properly collected, interpreted and used, have much to contribute to the appropriateness and effectiveness of humanitarian action in emergencies, and to advocacy on behalf of populations in crises. Most actors involved in relief will one day be confronted by such data, but the different ways in which this information can be collected, and their potential pitfalls, are not yet common knowledge among non-epidemiologists. </p>
<p><span style="line-height:1.6em">This network paper describes the practice and purpose of that branch of epidemiology concerned with population mortality. It sets out the key indicators used to express mortality data, different options for how to measure mortality rates and suggestions for how to assess, interpret and use mortality reports. The paper also discusses the politics of mortality figures. </span></p>
<p><span style="line-height:1.6em">The paper’s aim is to enable readers to critically interpret mortality study reports, and to understand how these are used (or misused) to formulate policy. The intended audience is therefore all humanitarian actors, policy-makers, the media and members of affected communities, who may be called upon to comment on or make use of mortality studies, regardless of their technical background. </span></p>