Guidance to undertaking systematic evidence maps
Hanan Khalil, Vivian Welsh, Matthew Grainger, Fiona Campbell
Abstract
• This commentary provides Practical, stepwise SEM workflow with tool examples. • SEMs map research landscapes to identify trends and gaps across disciplines. • SEMs use systematic searches, set criteria, and visual tools to categorise research. • SEMs face issues like unclear terms, no synthesis, and weak visuals for decisions. Systematic Evidence Maps (SEMs) are a form of evidence synthesis offering structured approaches to categorizing and organizing scientific evidence by identifying trends and gaps. SEMs support researchers and policymakers in navigating complex evidence landscapes. By synthesizing evidence, they lay the foundation for targeted systematic reviews and primary research, supporting evidence-informed decision-making. These outputs can be hosted on websites, providing an interactive tool. In environmental health, SEMs are systematically used to categorize evidence on topics such as pollution control measures, climate change impacts, and health disparities. The methodological framework for conducting SEMs involves defining the research scope, employing a systematic search strategy, screening studies systematically, optionally conducting critical appraisal (risk of bias assessment) when studies are categorized by effect direction or intended to inform subsequent syntheses, and coding data for synthesis and visualization. Narrative synthesis, heatmaps, network diagrams, and evidence gap maps enhance SEM usability. However, challenges remain, including methodological inconsistencies and the need for standardization. Advances in automation, machine learning, and stakeholder engagement can further refine SEM methodologies. This commentary situates SEMs within the broader family of evidence synthesis, emphasizing their role in environmental health science. By enhancing methodological clarity and leveraging innovative tools, SEMs can support researchers and decision-makers in navigating complex evidence ecosystems and implementing evidence-based solutions for environmental scientists.