--- title: "Evidence Types Catalog" description: "Different claims require different types of evidence. This catalog describes evidence types, their strengths and limitations, and when each is most appropriate." type: skill canonical_url: https://claudary.paisolsolutions.com/skills/evidence-types-catalog source: "Claudary" difficulty: intermediate author: "Claude Code Knowledge Pack" date: 2026-07-10T11:24:21.316Z license: CC-BY-4.0 attribution: "Evidence Types Catalog — Claudary (https://claudary.paisolsolutions.com/skills/evidence-types-catalog)" --- # Evidence Types Catalog Different claims require different types of evidence. This catalog describes evidence types, their strengths and limitations, and when each is most appropriate. ## Overview # Evidence Types Catalog Different claims require different types of evidence. This catalog describes evidence types, their strengths and limitations, and when each is most appropriate. --- ## Overview: Matching Evidence to Claims | Claim Type | Best Evidence Types | | ------------------------ | ------------------------------------------ | | "X causes Y" | Experimental, Statistical, Longitudinal | | "X is widespread" | Statistical, Survey, Multiple Case Studies | | "X works in practice" | Case Study, Testimonial, Experimental | | "Experts believe X" | Expert Quote, Survey of Experts | | "X has always been true" | Historical, Longitudinal | | "X feels like Y" | Anecdotal, Phenomenological | | "X is the best approach" | Comparative, Experimental, Case Study | --- ## Evidence Types ### 1. Statistical Evidence **What it is:** Numerical data from systematic measurement or research. **Subtypes:** - Descriptive statistics (averages, percentages, distributions) - Inferential statistics (correlations, significance tests) - Population data (census, surveys) - Longitudinal data (trends over time) **Strengths:** - Quantifiable and precise - Can show patterns across large populations - Harder to dismiss than anecdote - Can demonstrate magnitude and scale **Limitations:** - Numbers can be misleading without context - Correlation ≠ causation - Depends entirely on data quality - Can be manipulated through selection **Best for:** - Establishing prevalence or frequency - Showing trends and patterns - Demonstrating magnitude of a problem - Comparing groups or conditions **Quality markers:** - Sample size adequate - Methodology transparent - Confidence intervals provided - Limitations acknowledged --- ### 2. Case Study Evidence **What it is:** Detailed examination of specific real-world examples. **Subtypes:** - Organizational case studies (companies, institutions) - Individual case studies (people, projects) - Historical case studies (events, decisions) - Comparative case studies (multiple examples examined together) **Strengths:** - Rich, detailed, and engaging - Shows how things work in practice - Memorable and persuasive - Can illustrate complex interactions **Limitations:** - May not generalize - Selection bias (why this case?) - Often lacks counterfactual - Details can be wrong or idealized **Best for:** - Illustrating principles in action - Making abstract concepts concrete - Providing memorable examples - Showing practical application **Quality markers:** - Named and verifiable entities - Specific details and outcomes - Sources for key facts - Acknowledgment of limitations --- ### 3. Expert Testimony **What it is:** Statements from recognized authorities in the relevant field. **Subtypes:** - Direct quotes from experts - Expert opinion in publications - Expert consensus statements - Expert disagreement/debate **Strengths:** - Borrows credibility from the expert - Can provide synthesis and interpretation - Signals that smart people agree - Adds authority to claims **Limitations:** - Expert opinion ≠ empirical evidence - Experts can be wrong - Appeal to authority fallacy risk - Experts may have conflicts of interest **Best for:** - Establishing current thinking in a field - Interpreting complex evidence - Adding credibility to conclusions - Identifying open questions **Quality markers:** - Expert has relevant credentials - Quote is in context - Multiple experts if citing consensus - Dissenting views acknowledged --- ### 4. Historical Evidence **What it is:** Information about past events, developments, and contexts. **Subtypes:** - Primary historical documents - Historical analysis by scholars - Chronological development - Historical analogies **Strengths:** - Establishes origins and development - Provides perspective and context - Shows what has been tried before - Can reveal patterns over time **Limitations:** - Historical conditions may differ from present - Records may be incomplete or biased - Hindsight bias can distort interpretation - Historical analogies can mislead **Best for:** - Establishing context and background - Showing development over time - Learning from past successes/failures - Grounding current discussions **Quality markers:** - Primary sources used when available - Context acknowledged - Multiple perspectives considered - Limitations of historical analogy noted --- ### 5. Experimental Evidence **What it is:** Results from controlled experiments designed to test specific hypotheses. **Subtypes:** - Randomized controlled trials (gold standard) - Laboratory experiments - Field experiments - Natural experiments **Strengths:** - Can establish causation (not just correlation) - Controls for confounding variables - Reproducible in principle - Considered strongest evidence type **Limitations:** - Often narrow scope - Lab conditions may not reflect real world - Expensive and time-consuming - Ethical limits on what can be tested **Best for:** - Establishing causal relationships - Testing specific hypotheses - Comparing interventions - Settling empirical debates **Quality markers:** - Random assignment - Adequate sample size - Pre-registration of hypotheses - Replication by other researchers --- ### 6. Survey/Poll Evidence **What it is:** Systematic collection of opinions, behaviors, or characteristics from a sample. **Subtypes:** - Public opinion polls - Academic surveys - Industry surveys - Internal organizational surveys **Strengths:** - Can capture attitudes and beliefs - Can measure self-reported behavior - Relatively fast and scalable - Can track changes over time **Limitations:** - Self-report bias - Question wording effects - Sampling challenges - Response rates matter **Best for:** - Understanding attitudes and beliefs - Measuring prevalence of behaviors - Capturing self-reported experiences - Identifying trends **Quality markers:** - Methodology disclosed - Sample is representative - Response rate adequate - Question wording neutral --- ### 7. Anecdotal Evidence **What it is:** Individual stories, personal experiences, or illustrative examples. **Subtypes:** - Personal stories - Illustrative examples - Testimonials - Observational accounts **Strengths:** - Highly engaging and memorable - Makes abstract concepts vivid - Connects emotionally - Can illustrate what statistics can't capture **Limitations:** - Doesn't generalize - Subject to selection bias - Can be atypical or misleading - Easy to find anecdotes for any position **Best for:** - Opening chapters or sections - Illustrating points made with other evidence - Humanizing data - Engaging reader emotionally **Quality markers:** - Presented as illustration, not proof - Verifiable if possible - Representative of broader patterns - Not cherry-picked outlier --- ### 8. Observational Evidence **What it is:** Systematic observation without experimental intervention. **Subtypes:** - Ethnographic observation - Naturalistic studies - Cohort studies - Cross-sectional studies **Strengths:** - Studies real-world conditions - Can capture complex phenomena - Doesn't require intervention - Can study rare events or long timeframes **Limitations:** - Cannot establish causation - Observer may influence observed - Confounding variables uncontrolled - Selection bias possible **Best for:** - Understanding phenomena in context - Generating hypotheses - Studying things that can't be experimentally manipulated - Documenting patterns **Quality markers:** - Systematic methodology - Multiple observers when possible - Limitations acknowledged - Triangulation with other evidence types --- ### 9. Counterargument Evidence **What it is:** Evidence that challenges or complicates the main thesis. **Subtypes:** - Direct refutation - Competing theories - Edge cases and exceptions - Methodological critiques **Strengths:** - Demonstrates intellectual honesty - Strengthens credibility - Prepares reader for objections - Shows depth of engagement **Limitations:** - Can undermine argument if not handled well - May confuse readers if overemphasized - Requires skill to integrate **Best for:** - Building trust with skeptical readers - Addressing obvious objections preemptively - Showing nuance - Demonstrating balanced perspective **Quality markers:** - Strongest version presented (steelman) - Response provided - Not straw-manned - Acknowledges valid points --- ### 10. Comparative Evidence **What it is:** Evidence from comparing different conditions, approaches, or groups. **Subtypes:** - Cross-cultural comparisons - Before/after comparisons - Treatment vs. control comparisons - Benchmarking **Strengths:** - Shows what's possible under different conditions - Provides concrete alternatives - Can control for some variables - Often very persuasive **Limitations:** - Comparisons may not be apples-to-apples - Confounding differences between groups - Success may not transfer across contexts **Best for:** - Showing alternatives work - Demonstrating impact of interventions - Identifying best practices - Making the case for change **Quality markers:** - Comparisons are genuinely comparable - Key differences acknowledged - Not cherry-picked comparisons - Mechanism for difference explained --- ## Evidence Combinations Strong arguments typically combine multiple evidence types: ### For Persuasion 1. **Hook:** Anecdotal (engagement) 2. **Scale:** Statistical (magnitude) 3. **Mechanism:** Experimental or Expert (explanation) 4. **Application:** Case Study (practical) 5. **Credibility:** Address Counterarguments (trust) ### For Establishing New Ideas 1. **Foundation:** Historical (context) 2. **Theory:** Expert (framework) 3. **Test:** Experimental (validation) 4. **Application:** Case Study (real-world) ### For Challenging Conventional Wisdom 1. **Contrast:** Counterargument (what people think) 2. **Evidence:** Statistical or Experimental (what's actually true) 3. **Explanation:** Expert (why the misconception exists) 4. **Proof:** Case Study (examples of the truth) --- ## Matching Evidence to Proof Burden | Proof Burden Level | Evidence Needed | | -------------------------------- | --------------------------------------------------------------------- | | **Heavy** (extraordinary claims) | Experimental + Statistical + Multiple Case Studies + Expert consensus | | **Medium** (significant claims) | Statistical or Experimental + Case Studies + Expert support | | **Light** (supporting points) | Case Study or Expert quote + Anecdotal illustration | | **Minimal** (common knowledge) | Brief reference or single example | --- _Use this catalog when specifying evidence types in research prompts and when evaluating whether returned research meets the chapter's needs._ --- Source: [Claudary](https://claudary.paisolsolutions.com/skills/evidence-types-catalog) · https://claudary.paisolsolutions.com