Evidence hierarchy

Evidence hierarchy is a system that ranks different types of information based on their reliability and strength. At the top are systematic reviews and meta-analyses, which analyze many studies to draw conclusions. Next come randomized controlled trials, where participants are assigned randomly to reduce bias. Following are cohort studies, then case-control studies, and finally expert opinions and anecdotal evidence at the bottom. This hierarchy helps determine which sources of information are most trustworthy and valuable for making informed decisions, especially in fields like medicine and research.