Evidence Quality and Source Evaluation
Evaluate sources using evidence quality frameworks, understanding the hierarchy of evidence and its limitations.
A systematic review of randomized controlled trials is stronger evidence than a single case study. Understanding the hierarchy of evidence helps you evaluate the strength of claims, not just the credibility of sources.
The Evidence Hierarchy
Different types of evidence provide different levels of certainty. The evidence hierarchy, developed in medicine but applicable broadly, ranks evidence types from strongest to weakest.
- Systematic reviews and meta-analyses: Synthesize findings from multiple studies
- Randomized controlled trials (RCTs): Gold standard for causal claims
- Cohort and case-control studies: Observational studies with comparison groups
- Case series and case reports: Observations without comparison groups
- Expert opinion and editorials: Weakest form of evidence
Many misleading claims confuse correlation with causation. Ice cream sales and drowning rates are correlated (both increase in summer) but ice cream does not cause drowning. Always ask: Is there a plausible causal mechanism? Have confounding variables been controlled for?
Combine CRAAP criteria with evidence quality assessment. A source can be authoritative (high CRAAP score) but present weak evidence (low on the evidence hierarchy). Both dimensions matter.
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3 questions · Grade 9 level