Systematic Reviews

Develop Research Question

A well-defined research question is the cornerstone of any systematic review. Begin by clarifying the clinical or research problem you wish to address. Use frameworks such as PICO (Population, Intervention, Comparison, Outcome) to structure your question, ensuring it is specific, answerable, and relevant to your field. This process helps guide your review’s scope, informs your search strategy, and sets the stage for reproducible results.

Learn more about PICO

Other Frameworks

While PICO is widely used for clinical research questions, other frameworks are better suited for different types of evidence synthesis. For example, SPIDER is often used for qualitative research, PEO for public health or social science topics, and ECLIPSE for policy or service evaluations. Choosing the right framework helps ensure your question is structured appropriately for the type of review you're conducting.

View this list of additional frameworks in a guide from the University of Maryland.

PICO(TS) Example and Hierarchy of Evidence

The optimal study design for answering a clinical question depends on the type of question being asked. Different research questions—such as those about therapy, diagnosis, prognosis, or harm—require different types of evidence. The chart below outlines the hierarchy of evidence typically sought for each question type, helping guide the selection of appropriate studies during the literature search phase of a systematic review.