Issue: Humanitarian actors and researchers have amassed evidence, but synthesizing this information and communicating it to policymakers and practitioners remains challenging. Although all reviews face methodological challenges, the context for humanitarian evidence is fundamentally different from the medical trial context from which systematic reviews emerged. The settings – which often involve active armed conflict, natural disasters, or the immediate aftermath of conflict or disasters – render data collection difficult or impossible. When data exist, the reliability, representativeness, and generalisability may be limited by access and numerous biases, including selection, recall, and reporting bias. Even in humanitarian settings that are not characterized by instability or insecurity, the types of studies can be limited by the fragility of protracted crises, the sensitivity of the information, and issues related to identifying and accessing affected populations.
Response: As a response to this context and the low-level of understanding around systematic reviews in the humanitarian field, the Humanitarian Evidence Programme brought together and adapted existing literature for a guidance note on evidence synthesis in the humanitarian sector. Building on work from Cochrane, EvidenceAid, Overseas Development Institute, and 3ie, this note presents technical guidance in a manner accessible to an audience with a strong humanitarian identity. One challenge is to synthesize and communicate 'low-confidence' qualitative evidence. All of our evidence synthesis outputs strive to be transparent about which evidence they synthesize, clear about gaps and limits in the literature, and systematic in their mode of analysis of existing research. The guidance note is currently being used for a number of reviews, from acute malnutrition to shelter and settlement strategies. As with other reviews, the Humanitarian Evidence Programme reviews hope to identify gaps in existing research and knowledge, form conclusions with greater confidence than with individual studies, showcase disagreement and diversity among the literature, and highlight opportunities for further research.