Among the following options, which evidence type is positioned toward the bottom of the evidence pyramid?

Among the following options, which evidence type is positioned toward the bottom of the evidence pyramid?

• A. Systematic review of descriptive studies
• B. Single qualitative study
• C. Randomized controlled trial
• D. Meta-analysis

Answer: (B)

Evidence hierarchy ranks study designs by how well they minimize bias and generalize findings. A single qualitative study sits toward the bottom because, while it provides rich, contextual insights, its findings come from one setting with a small sample and lack replication or statistical power to show consistent effects across different populations. This limits transferability and the strength of conclusions. In contrast, randomized controlled trials actively reduce bias through randomization, and meta-analyses combine data from multiple studies to yield more precise estimates. A systematic review of descriptive studies may synthesize more findings than one study, but it still doesn’t offer the causal inference and broad applicability that higher-tier designs provide. So the single qualitative study is placed toward the bottom of the evidence pyramid.

Evidence hierarchy ranks study designs by how well they minimize bias and generalize findings. A single qualitative study sits toward the bottom because, while it provides rich, contextual insights, its findings come from one setting with a small sample and lack replication or statistical power to show consistent effects across different populations. This limits transferability and the strength of conclusions. In contrast, randomized controlled trials actively reduce bias through randomization, and meta-analyses combine data from multiple studies to yield more precise estimates. A systematic review of descriptive studies may synthesize more findings than one study, but it still doesn’t offer the causal inference and broad applicability that higher-tier designs provide. So the single qualitative study is placed toward the bottom of the evidence pyramid.