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---
name: hypothesis-generation
description: "Generate testable hypotheses. Formulate from observations, design experiments, explore competing explanations, develop predictions, propose mechanisms, for scientific inquiry across domains."
---
# Scientific Hypothesis Generation
## Overview
Hypothesis generation is a systematic process for developing testable explanations. Formulate evidence-based hypotheses from observations, design experiments, explore competing explanations, and develop predictions. Apply this skill for scientific inquiry across domains.
## When to Use This Skill
This skill should be used when:
- Developing hypotheses from observations or preliminary data
- Designing experiments to test scientific questions
- Exploring competing explanations for phenomena
- Formulating testable predictions for research
- Conducting literature-based hypothesis generation
- Planning mechanistic studies across scientific domains
## Workflow
Follow this systematic process to generate robust scientific hypotheses:
### 1. Understand the Phenomenon
Start by clarifying the observation, question, or phenomenon that requires explanation:
- Identify the core observation or pattern that needs explanation
- Define the scope and boundaries of the phenomenon
- Note any constraints or specific contexts
- Clarify what is already known vs. what is uncertain
- Identify the relevant scientific domain(s)
### 2. Conduct Comprehensive Literature Search
Search existing scientific literature to ground hypotheses in current evidence. Use both PubMed (for biomedical topics) and general web search (for broader scientific domains):
**For biomedical topics:**
- Use WebFetch with PubMed URLs to access relevant literature
- Search for recent reviews, meta-analyses, and primary research
- Look for similar phenomena, related mechanisms, or analogous systems
**For all scientific domains:**
- Use WebSearch to find recent papers, preprints, and reviews
- Search for established theories, mechanisms, or frameworks
- Identify gaps in current understanding
**Search strategy:**
- Begin with broad searches to understand the landscape
- Narrow to specific mechanisms, pathways, or theories
- Look for contradictory findings or unresolved debates
- Consult `references/literature_search_strategies.md` for detailed search techniques
### 3. Synthesize Existing Evidence
Analyze and integrate findings from literature search:
- Summarize current understanding of the phenomenon
- Identify established mechanisms or theories that may apply
- Note conflicting evidence or alternative viewpoints
- Recognize gaps, limitations, or unanswered questions
- Identify analogies from related systems or domains
### 4. Generate Competing Hypotheses
Develop 3-5 distinct hypotheses that could explain the phenomenon. Each hypothesis should:
- Provide a mechanistic explanation (not just description)
- Be distinguishable from other hypotheses
- Draw on evidence from the literature synthesis
- Consider different levels of explanation (molecular, cellular, systemic, population, etc.)
**Strategies for generating hypotheses:**
- Apply known mechanisms from analogous systems
- Consider multiple causative pathways
- Explore different scales of explanation
- Question assumptions in existing explanations
- Combine mechanisms in novel ways
### 5. Evaluate Hypothesis Quality
Assess each hypothesis against established quality criteria from `references/hypothesis_quality_criteria.md`:
**Testability:** Can the hypothesis be empirically tested?
**Falsifiability:** What observations would disprove it?
**Parsimony:** Is it the simplest explanation that fits the evidence?
**Explanatory Power:** How much of the phenomenon does it explain?
**Scope:** What range of observations does it cover?
**Consistency:** Does it align with established principles?
**Novelty:** Does it offer new insights beyond existing explanations?
Explicitly note the strengths and weaknesses of each hypothesis.
### 6. Design Experimental Tests
For each viable hypothesis, propose specific experiments or studies to test it. Consult `references/experimental_design_patterns.md` for common approaches:
**Experimental design elements:**
- What would be measured or observed?
- What comparisons or controls are needed?
- What methods or techniques would be used?
- What sample sizes or statistical approaches are appropriate?
- What are potential confounds and how to address them?
**Consider multiple approaches:**
- Laboratory experiments (in vitro, in vivo, computational)
- Observational studies (cross-sectional, longitudinal, case-control)
- Clinical trials (if applicable)
- Natural experiments or quasi-experimental designs
### 7. Formulate Testable Predictions
For each hypothesis, generate specific, quantitative predictions:
- State what should be observed if the hypothesis is correct
- Specify expected direction and magnitude of effects when possible
- Identify conditions under which predictions should hold
- Distinguish predictions between competing hypotheses
- Note predictions that would falsify the hypothesis
### 8. Present Structured Output
Use the template in `assets/hypothesis_output_template.md` to present hypotheses in a clear, consistent format:
**Standard structure:**
1. **Background & Context** - Phenomenon and literature summary
2. **Competing Hypotheses** - Enumerated hypotheses with mechanistic explanations
3. **Quality Assessment** - Evaluation of each hypothesis
4. **Experimental Designs** - Proposed tests for each hypothesis
5. **Testable Predictions** - Specific, measurable predictions
6. **Critical Comparisons** - How to distinguish between hypotheses
## Quality Standards
Ensure all generated hypotheses meet these standards:
- **Evidence-based:** Grounded in existing literature with citations
- **Testable:** Include specific, measurable predictions
- **Mechanistic:** Explain how/why, not just what
- **Comprehensive:** Consider alternative explanations
- **Rigorous:** Include experimental designs to test predictions
## Resources
### references/
- `hypothesis_quality_criteria.md` - Framework for evaluating hypothesis quality (testability, falsifiability, parsimony, explanatory power, scope, consistency)
- `experimental_design_patterns.md` - Common experimental approaches across domains (RCTs, observational studies, lab experiments, computational models)
- `literature_search_strategies.md` - Effective search techniques for PubMed and general scientific sources
### assets/
- `hypothesis_output_template.md` - Structured format for presenting hypotheses consistently with all required sections

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# Scientific Hypothesis Generation: [Phenomenon Name]
## 1. Background & Context
### Phenomenon Description
[Clear description of the observation, pattern, or question that requires explanation. Include:
- What was observed or what question needs answering
- The specific context or system in which it occurs
- Any relevant constraints or boundary conditions
- Why this phenomenon is interesting or important]
### Current Understanding
[Synthesis of existing literature, including:
- What is already known about this phenomenon
- Established mechanisms or theories that may be relevant
- Key findings from recent research
- Gaps or limitations in current understanding
- Conflicting findings or unresolved debates
Include citations to key papers (Author et al., Year, Journal)]
### Knowledge Gaps
[Specific aspects that remain unexplained or poorly understood:
- What aspects of the phenomenon lack clear explanation?
- What contradictions exist in current understanding?
- What questions remain unanswered?]
---
## 2. Competing Hypotheses
### Hypothesis 1: [Concise Title]
**Mechanistic Explanation:**
[Detailed explanation of the proposed mechanism. This should explain HOW and WHY the phenomenon occurs, not just describe WHAT occurs. Include:
- Specific molecular, cellular, physiological, or population-level mechanisms
- Causal chain from initial trigger to observed outcome
- Key components, pathways, or factors involved
- Scale or level of explanation (molecular, cellular, organ, organism, population)]
**Supporting Evidence:**
[Evidence from literature that supports this hypothesis:
- Analogous mechanisms in related systems
- Direct evidence from relevant studies
- Theoretical frameworks that align with this hypothesis
- Include citations]
**Key Assumptions:**
[Explicit statement of assumptions underlying this hypothesis:
- What must be true for this hypothesis to hold?
- What conditions or contexts does it require?]
---
### Hypothesis 2: [Concise Title]
**Mechanistic Explanation:**
[Detailed mechanistic explanation distinct from Hypothesis 1]
**Supporting Evidence:**
[Evidence supporting this alternative explanation]
**Key Assumptions:**
[Assumptions underlying this hypothesis]
---
### Hypothesis 3: [Concise Title]
**Mechanistic Explanation:**
[Detailed mechanistic explanation distinct from previous hypotheses]
**Supporting Evidence:**
[Evidence supporting this explanation]
**Key Assumptions:**
[Assumptions underlying this hypothesis]
---
[Continue for Hypothesis 4, 5, etc. if applicable]
---
## 3. Quality Assessment
### Evaluation Against Core Criteria
| Criterion | Hypothesis 1 | Hypothesis 2 | Hypothesis 3 | [H4] | [H5] |
|-----------|--------------|--------------|--------------|------|------|
| **Testability** | [Rating & brief note] | [Rating & brief note] | [Rating & brief note] | | |
| **Falsifiability** | [Rating & brief note] | [Rating & brief note] | [Rating & brief note] | | |
| **Parsimony** | [Rating & brief note] | [Rating & brief note] | [Rating & brief note] | | |
| **Explanatory Power** | [Rating & brief note] | [Rating & brief note] | [Rating & brief note] | | |
| **Scope** | [Rating & brief note] | [Rating & brief note] | [Rating & brief note] | | |
| **Consistency** | [Rating & brief note] | [Rating & brief note] | [Rating & brief note] | | |
**Rating scale:** Strong / Moderate / Weak
### Detailed Evaluation
#### Hypothesis 1
**Strengths:**
- [Specific strength 1]
- [Specific strength 2]
**Weaknesses:**
- [Specific weakness 1]
- [Specific weakness 2]
**Overall Assessment:**
[Brief summary of hypothesis quality and viability]
#### Hypothesis 2
[Similar structure]
#### Hypothesis 3
[Similar structure]
---
## 4. Experimental Designs
### Testing Hypothesis 1: [Title]
**Experiment 1A: [Brief title]**
*Design Type:* [e.g., In vitro dose-response / In vivo knockout / Clinical RCT / Observational cohort / Computational model]
*Objective:* [What specific aspect of the hypothesis does this test?]
*Methods:*
- **System/Model:** [What system, organism, or population?]
- **Intervention/Manipulation:** [What is varied or manipulated?]
- **Measurements:** [What outcomes are measured?]
- **Controls:** [What control conditions?]
- **Sample Size:** [Estimated n, with justification if possible]
- **Analysis:** [Statistical or analytical approach]
*Expected Timeline:* [Rough estimate]
*Feasibility:* [High/Medium/Low, with brief justification]
**Experiment 1B: [Brief title - alternative or complementary approach]**
[Similar structure to 1A]
---
### Testing Hypothesis 2: [Title]
**Experiment 2A: [Brief title]**
[Structure as above]
**Experiment 2B: [Brief title]**
[Structure as above]
---
### Testing Hypothesis 3: [Title]
**Experiment 3A: [Brief title]**
[Structure as above]
---
## 5. Testable Predictions
### Predictions from Hypothesis 1
1. **Prediction 1.1:** [Specific, measurable prediction]
- **Conditions:** [Under what conditions should this be observed?]
- **Magnitude:** [Expected effect size or direction, if quantifiable]
- **Falsification:** [What observation would falsify this prediction?]
2. **Prediction 1.2:** [Specific, measurable prediction]
- **Conditions:** [Conditions]
- **Magnitude:** [Expected effect]
- **Falsification:** [Falsifying observation]
3. **Prediction 1.3:** [Additional prediction]
---
### Predictions from Hypothesis 2
1. **Prediction 2.1:** [Specific, measurable prediction]
- **Conditions:** [Conditions]
- **Magnitude:** [Expected effect]
- **Falsification:** [Falsifying observation]
2. **Prediction 2.2:** [Additional prediction]
---
### Predictions from Hypothesis 3
1. **Prediction 3.1:** [Specific, measurable prediction]
- **Conditions:** [Conditions]
- **Magnitude:** [Expected effect]
- **Falsification:** [Falsifying observation]
---
## 6. Critical Comparisons
### Distinguishing Between Hypotheses
**Comparison: Hypothesis 1 vs. Hypothesis 2**
*Key Distinguishing Feature:*
[What is the fundamental difference in mechanism or prediction?]
*Discriminating Experiment:*
[What experiment or observation would clearly favor one over the other?]
*Outcome Interpretation:*
- If [Result A], then Hypothesis 1 is supported
- If [Result B], then Hypothesis 2 is supported
- If [Result C], then both/neither are supported
---
**Comparison: Hypothesis 1 vs. Hypothesis 3**
[Similar structure]
---
**Comparison: Hypothesis 2 vs. Hypothesis 3**
[Similar structure]
---
### Priority Experiments
**Highest Priority Test:**
[Which experiment would most efficiently distinguish between hypotheses or most definitively test a hypothesis?]
**Justification:**
[Why is this the highest priority? Consider informativeness, feasibility, and cost]
**Secondary Priority Tests:**
1. [Second most important experiment]
2. [Third most important]
---
## 7. Summary & Recommendations
### Summary of Hypotheses
[Brief paragraph summarizing the competing hypotheses and their relationships]
### Recommended Testing Sequence
**Phase 1 (Initial Tests):**
[Which experiments should be done first? Why?]
**Phase 2 (Contingent on Phase 1 results):**
[What follow-up experiments depend on initial results?]
**Phase 3 (Validation and Extension):**
[How to validate findings and extend to broader contexts?]
### Expected Outcomes and Implications
**If Hypothesis 1 is supported:**
[What would this mean for the field? What new questions arise?]
**If Hypothesis 2 is supported:**
[Implications and new questions]
**If Hypothesis 3 is supported:**
[Implications and new questions]
**If multiple hypotheses are partially supported:**
[How might mechanisms combine or interact?]
### Open Questions
[What questions remain even after these hypotheses are tested?]
---
## References
[List key papers cited in the document, formatted consistently]
1. Author1, A.B., & Author2, C.D. (Year). Title of paper. *Journal Name*, Volume(Issue), pages. DOI or URL
2. [Continue for all citations]
---
## Notes on Using This Template
- Replace all bracketed instructions with actual content
- Not all sections are mandatory - adapt to your specific hypothesis generation task
- For simpler phenomena, 3 hypotheses may be sufficient; complex phenomena may warrant 4-5
- Experimental designs should be detailed enough to be actionable but can be refined later
- Predictions should be as specific and quantitative as possible
- The template emphasizes both generating hypotheses and planning how to test them
- Citation format can be adjusted to field-specific standards

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# Experimental Design Patterns
## Common Approaches to Testing Scientific Hypotheses
This reference provides patterns and frameworks for designing experiments across scientific domains. Use these patterns to develop rigorous tests for generated hypotheses.
## Design Selection Framework
Choose experimental approaches based on:
- **Nature of hypothesis:** Mechanistic, causal, correlational, descriptive
- **System studied:** In vitro, in vivo, computational, observational
- **Feasibility:** Time, cost, ethics, technical capabilities
- **Evidence needed:** Proof-of-concept, causal demonstration, quantitative relationship
## Laboratory Experimental Designs
### In Vitro Experiments
**When to use:** Testing molecular, cellular, or biochemical mechanisms in controlled systems.
**Common patterns:**
#### 1. Dose-Response Studies
- **Purpose:** Establish quantitative relationship between input and effect
- **Design:** Test multiple concentrations/doses of intervention
- **Key elements:**
- Negative control (no treatment)
- Positive control (known effective treatment)
- Multiple dose levels (typically 5-8 points)
- Technical replicates (≥3 per condition)
- Appropriate statistical analysis (curve fitting, IC50/EC50 determination)
**Example application:**
"To test if compound X inhibits enzyme Y, measure enzyme activity at 0, 1, 10, 100, 1000 nM compound X concentrations with n=3 replicates per dose."
#### 2. Gain/Loss of Function Studies
- **Purpose:** Establish causal role of specific component
- **Design:** Add (overexpression) or remove (knockout/knockdown) component
- **Key elements:**
- Wild-type control
- Gain-of-function condition (overexpression, constitutive activation)
- Loss-of-function condition (knockout, knockdown, inhibition)
- Rescue experiment (restore function to loss-of-function)
- Measure downstream effects
**Example application:**
"Test if protein X causes phenotype Y by: (1) knocking out X and observing phenotype loss, (2) overexpressing X and observing phenotype enhancement, (3) rescuing knockout with X re-expression."
#### 3. Time-Course Studies
- **Purpose:** Understand temporal dynamics and sequence of events
- **Design:** Measure outcomes at multiple time points
- **Key elements:**
- Time 0 baseline
- Early time points (capture rapid changes)
- Intermediate time points
- Late time points (steady state)
- Sufficient replication at each time point
**Example application:**
"Measure protein phosphorylation at 0, 5, 15, 30, 60, 120 minutes after stimulus to determine peak activation timing."
### In Vivo Experiments
**When to use:** Testing hypotheses in whole organisms to assess systemic, physiological, or behavioral effects.
**Common patterns:**
#### 4. Between-Subjects Designs
- **Purpose:** Compare different groups receiving different treatments
- **Design:** Randomly assign subjects to treatment groups
- **Key elements:**
- Random assignment to groups
- Appropriate sample size (power analysis)
- Control group (vehicle, sham, or standard treatment)
- Blinding (single or double-blind)
- Standardized conditions across groups
**Example application:**
"Randomly assign 20 mice each to vehicle control or drug treatment groups, measure tumor size weekly for 8 weeks, with experimenters blinded to group assignment."
#### 5. Within-Subjects (Repeated Measures) Designs
- **Purpose:** Each subject serves as own control, reducing inter-subject variability
- **Design:** Same subjects measured across multiple conditions/time points
- **Key elements:**
- Baseline measurements
- Counterbalancing (if order effects possible)
- Washout periods (for sequential treatments)
- Appropriate repeated-measures statistics
**Example application:**
"Measure cognitive performance in same participants at baseline, after training intervention, and at 3-month follow-up."
#### 6. Factorial Designs
- **Purpose:** Test multiple factors and their interactions simultaneously
- **Design:** Cross all levels of multiple independent variables
- **Key elements:**
- Clear main effects and interactions
- Sufficient power for interaction tests
- Full factorial or fractional factorial as appropriate
**Example application:**
"2×2 design crossing genotype (WT vs. mutant) × treatment (vehicle vs. drug) to test whether drug effect depends on genotype."
### Computational/Modeling Experiments
**When to use:** Testing hypotheses about complex systems, making predictions, or when physical experiments are infeasible.
#### 7. In Silico Simulations
- **Purpose:** Model complex systems, test theoretical predictions
- **Design:** Implement computational model and vary parameters
- **Key elements:**
- Well-defined model with explicit assumptions
- Parameter sensitivity analysis
- Validation against known data
- Prediction generation for experimental testing
**Example application:**
"Build agent-based model of disease spread, vary transmission rate and intervention timing, compare predictions to empirical epidemic data."
#### 8. Bioinformatics/Meta-Analysis
- **Purpose:** Test hypotheses using existing datasets
- **Design:** Analyze large-scale data or aggregate multiple studies
- **Key elements:**
- Appropriate statistical corrections (multiple testing)
- Validation in independent datasets
- Control for confounds and batch effects
- Clear inclusion/exclusion criteria
**Example application:**
"Test if gene X expression correlates with survival across 15 cancer datasets (n>5000 patients total), using Cox regression with clinical covariates."
## Observational Study Designs
### When Physical Manipulation is Impossible or Unethical
#### 9. Cross-Sectional Studies
- **Purpose:** Examine associations at a single time point
- **Design:** Measure variables of interest in population at one time
- **Strengths:** Fast, inexpensive, can establish prevalence
- **Limitations:** Cannot establish temporality or causation
- **Key elements:**
- Representative sampling
- Standardized measurements
- Control for confounding variables
- Appropriate statistical analysis
**Example application:**
"Survey 1000 adults to test association between diet pattern and biomarker X, controlling for age, sex, BMI, and physical activity."
#### 10. Cohort Studies (Prospective/Longitudinal)
- **Purpose:** Establish temporal relationships and potentially causal associations
- **Design:** Follow group over time, measuring exposures and outcomes
- **Strengths:** Can establish temporality, calculate incidence
- **Limitations:** Time-consuming, expensive, subject attrition
- **Key elements:**
- Baseline exposure assessment
- Follow-up at defined intervals
- Minimize loss to follow-up
- Account for time-varying confounders
**Example application:**
"Follow 5000 initially healthy individuals for 10 years, testing if baseline vitamin D levels predict cardiovascular disease incidence."
#### 11. Case-Control Studies
- **Purpose:** Efficiently study rare outcomes by comparing cases to controls
- **Design:** Identify cases with outcome, select matched controls, compare exposures
- **Strengths:** Efficient for rare diseases, relatively quick
- **Limitations:** Recall bias, selection bias, cannot calculate incidence
- **Key elements:**
- Clear case definition
- Appropriate control selection (matching or statistical adjustment)
- Retrospective exposure assessment
- Control for confounding
**Example application:**
"Compare 200 patients with rare disease X to 400 matched controls without X, testing if early-life exposure Y differs between groups."
## Clinical Trial Designs
#### 12. Randomized Controlled Trials (RCTs)
- **Purpose:** Gold standard for testing interventions in humans
- **Design:** Randomly assign participants to treatment or control
- **Key elements:**
- Randomization (simple, block, or stratified)
- Concealment of allocation
- Blinding (participants, providers, assessors)
- Intention-to-treat analysis
- Pre-registered protocol and analysis plan
**Example application:**
"Double-blind RCT: randomly assign 300 patients to receive drug X or placebo for 12 weeks, measure primary outcome of symptom improvement."
#### 13. Crossover Trials
- **Purpose:** Each participant receives all treatments in sequence
- **Design:** Participants crossed over between treatments with washout
- **Strengths:** Reduces inter-subject variability, requires fewer participants
- **Limitations:** Order effects, requires reversible conditions, longer duration
- **Key elements:**
- Adequate washout period
- Randomized treatment order
- Carryover effect assessment
**Example application:**
"Crossover trial: participants receive treatment A for 4 weeks, 2-week washout, then treatment B for 4 weeks (randomized order)."
## Advanced Design Considerations
### Sample Size and Statistical Power
**Key questions:**
- What effect size is meaningful to detect?
- What statistical test will be used?
- What alpha (significance level) and beta (power) are appropriate?
- What is expected variability in the measurement?
**General guidelines:**
- Conduct formal power analysis before experiment
- For pilot studies, n≥10 per group minimum
- For definitive studies, aim for ≥80% power
- Account for potential attrition in longitudinal studies
### Controls
**Types of controls:**
- **Negative control:** No intervention (baseline)
- **Positive control:** Known effective intervention (validates system)
- **Vehicle control:** Delivery method without active ingredient
- **Sham control:** Mimics intervention without active component (surgery, etc.)
- **Historical control:** Prior data (weakest, avoid if possible)
### Blinding
**Levels:**
- **Open-label:** No blinding (acceptable for objective measures)
- **Single-blind:** Participants blinded (reduces placebo effects)
- **Double-blind:** Participants and experimenters blinded (reduces bias in assessment)
- **Triple-blind:** Participants, experimenters, and analysts blinded (strongest)
### Replication
**Technical replicates:** Repeated measurements on same sample
- Reduce measurement error
- Typically 2-3 replicates sufficient
**Biological replicates:** Independent samples/subjects
- Address biological variability
- Critical for generalization
- Minimum: n≥3, preferably n≥5-10 per group
**Experimental replicates:** Repeat entire experiment
- Validate findings across time, equipment, operators
- Gold standard for confirming results
### Confound Control
**Strategies:**
- **Randomization:** Distribute confounds evenly across groups
- **Matching:** Pair similar subjects across conditions
- **Blocking:** Group by confound, then randomize within blocks
- **Statistical adjustment:** Measure confounds and adjust in analysis
- **Standardization:** Keep conditions constant across groups
## Selecting Appropriate Design
**Decision tree:**
1. **Can variables be manipulated?**
- Yes → Experimental design (RCT, lab experiment)
- No → Observational design (cohort, case-control, cross-sectional)
2. **What is the system?**
- Cells/molecules → In vitro experiments
- Whole organisms → In vivo experiments
- Humans → Clinical trials or observational studies
- Complex systems → Computational modeling
3. **What is the primary goal?**
- Mechanism → Gain/loss of function, dose-response
- Causation → RCT, cohort study with good controls
- Association → Cross-sectional, case-control
- Prediction → Modeling, machine learning
- Temporal dynamics → Time-course, longitudinal
4. **What are the constraints?**
- Time limited → Cross-sectional, in vitro
- Budget limited → Computational, observational
- Ethical concerns → Observational, in vitro
- Rare outcome → Case-control, meta-analysis
## Integrating Multiple Approaches
Strong hypothesis testing often combines multiple designs:
**Example: Testing if microbiome affects cognitive function**
1. **Observational:** Cohort study showing association between microbiome composition and cognition
2. **Animal model:** Germ-free mice receiving microbiome transplants show cognitive changes
3. **Mechanism:** In vitro studies showing microbial metabolites affect neuronal function
4. **Clinical trial:** RCT of probiotic intervention improving cognitive scores
5. **Computational:** Model predicting which microbiome profiles should affect cognition
**Triangulation approach:**
- Each design addresses different aspects/limitations
- Convergent evidence from multiple approaches strengthens causal claims
- Start with observational/in vitro, then move to definitive causal tests
## Common Pitfalls
- Insufficient sample size (underpowered)
- Lack of appropriate controls
- Confounding variables not accounted for
- Inappropriate statistical tests
- P-hacking or multiple testing without correction
- Lack of blinding when subjective assessments involved
- Failure to replicate findings
- Not pre-registering analysis plans (clinical trials)
## Practical Application for Hypothesis Testing
When designing experiments to test hypotheses:
1. **Match design to hypothesis specifics:** Causal claims require experimental manipulation; associations can use observational designs
2. **Start simple, then elaborate:** Pilot with simple design, then add complexity
3. **Plan controls carefully:** Controls validate the system and isolate the specific effect
4. **Consider feasibility:** Balance ideal design with practical constraints
5. **Plan for multiple experiments:** Rarely does one experiment definitively test a hypothesis
6. **Pre-specify analysis:** Decide statistical tests before data collection
7. **Build in validation:** Independent replication, orthogonal methods, convergent evidence

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# Hypothesis Quality Criteria
## Framework for Evaluating Scientific Hypotheses
Use these criteria to assess the quality and rigor of generated hypotheses. A robust hypothesis should score well across multiple dimensions.
## Core Criteria
### 1. Testability
**Definition:** The hypothesis can be empirically tested through observation or experimentation.
**Evaluation questions:**
- Can specific experiments or observations test this hypothesis?
- Are the predicted outcomes measurable?
- Can the hypothesis be tested with current or near-future methods?
- Are there multiple independent ways to test it?
**Strong testability examples:**
- "Increased expression of protein X will reduce cell proliferation rate by >30%"
- "Patients receiving treatment Y will show 50% reduction in symptom Z within 4 weeks"
**Weak testability examples:**
- "This process is influenced by complex interactions" (vague, no specific prediction)
- "The mechanism involves quantum effects" (if no method to test quantum effects exists)
### 2. Falsifiability
**Definition:** Clear conditions or observations would disprove the hypothesis (Popperian criterion).
**Evaluation questions:**
- What specific observations would prove this hypothesis wrong?
- Are the falsifying conditions realistic to observe?
- Is the hypothesis stated clearly enough to be disproven?
- Can null results meaningfully falsify the hypothesis?
**Strong falsifiability examples:**
- "If we knock out gene X, phenotype Y will disappear" (can be falsified if phenotype persists)
- "Drug A will outperform placebo in 80% of patients" (clear falsification threshold)
**Weak falsifiability examples:**
- "Multiple factors contribute to the outcome" (too vague to falsify)
- "The effect may vary depending on context" (built-in escape clauses)
### 3. Parsimony (Occam's Razor)
**Definition:** Among competing hypotheses with equal explanatory power, prefer the simpler explanation.
**Evaluation questions:**
- Does the hypothesis invoke the minimum number of entities/mechanisms needed?
- Are all proposed elements necessary to explain the phenomenon?
- Could a simpler mechanism account for the observations?
- Does it avoid unnecessary assumptions?
**Parsimony considerations:**
- Simple ≠ simplistic; complexity is justified when evidence demands it
- Established mechanisms are "simpler" than novel, unproven ones
- Direct mechanisms are simpler than elaborate multi-step pathways
- One well-supported mechanism beats multiple speculative ones
### 4. Explanatory Power
**Definition:** The hypothesis accounts for a substantial portion of the observed phenomenon.
**Evaluation questions:**
- How much of the observed data does this hypothesis explain?
- Does it account for both typical and atypical observations?
- Can it explain related phenomena beyond the immediate observation?
- Does it resolve apparent contradictions in existing data?
**Strong explanatory power indicators:**
- Explains multiple independent observations
- Accounts for quantitative relationships, not just qualitative patterns
- Resolves previously puzzling findings
- Makes sense of seemingly contradictory results
**Limited explanatory power indicators:**
- Only explains part of the phenomenon
- Requires additional hypotheses for complete explanation
- Leaves major observations unexplained
### 5. Scope
**Definition:** The range of phenomena and contexts the hypothesis can address.
**Evaluation questions:**
- Does it apply only to the specific case or to broader situations?
- Can it generalize across conditions, species, or systems?
- Does it connect to larger theoretical frameworks?
- What are its boundaries and limitations?
**Broader scope (generally preferable):**
- Applies across multiple experimental conditions
- Generalizes to related systems or species
- Connects phenomenon to established principles
**Narrower scope (acceptable if explicitly defined):**
- Limited to specific conditions or contexts
- Requires different mechanisms in different settings
- Context-dependent with clear boundaries
### 6. Consistency with Established Knowledge
**Definition:** Alignment with well-supported theories, principles, and empirical findings.
**Evaluation questions:**
- Is it consistent with established physical, chemical, or biological principles?
- Does it align with or reasonably extend current theories?
- If contradicting established knowledge, is there strong justification?
- Does it require violating well-supported laws or findings?
**Levels of consistency:**
- **Fully consistent:** Applies established mechanisms in new context
- **Mostly consistent:** Extends current understanding in plausible ways
- **Partially inconsistent:** Contradicts some findings but has explanatory value
- **Highly inconsistent:** Requires rejecting well-established principles (requires exceptional evidence)
### 7. Novelty and Insight
**Definition:** The hypothesis offers new understanding beyond merely restating known facts.
**Evaluation questions:**
- Does it provide new mechanistic insight?
- Does it challenge assumptions or conventional wisdom?
- Does it suggest unexpected connections or relationships?
- Does it open new research directions?
**Novel contributions:**
- Proposes previously unconsidered mechanisms
- Reframes the problem in a productive way
- Connects disparate observations
- Suggests non-obvious testable predictions
**Note:** Novelty alone doesn't make a hypothesis valuable; it must also be testable, parsimonious, and explanatory.
## Comparative Evaluation
When evaluating multiple competing hypotheses:
### Trade-offs and Balancing
Hypotheses often involve trade-offs:
- More parsimonious but less explanatory power
- Broader scope but less testable with current methods
- Novel insights but less consistent with current knowledge
**Evaluation approach:**
- No hypothesis needs to be perfect on all dimensions
- Identify each hypothesis's strengths and weaknesses
- Consider which criteria are most important for the specific phenomenon
- Note which hypotheses are most immediately testable
- Identify which would be most informative if supported
### Distinguishability
**Key question:** Can experiments distinguish between competing hypotheses?
- Identify predictions that differ between hypotheses
- Prioritize hypotheses that make distinct predictions
- Note which experiments would most efficiently narrow the field
- Consider whether hypotheses could all be partially correct
## Common Pitfalls
### Untestable Hypotheses
- Too vague to generate specific predictions
- Invoke unobservable or unmeasurable entities
- Require technology that doesn't exist
### Unfalsifiable Hypotheses
- Built-in escape clauses ("may or may not occur")
- Post-hoc explanations that fit any outcome
- No specification of what would disprove them
### Overly Complex Hypotheses
- Invoke multiple unproven mechanisms
- Add unnecessary steps or entities
- Complexity not justified by explanatory gains
### Just-So Stories
- Plausible narratives without testable predictions
- Explain observations but don't predict new ones
- Impossible to distinguish from alternative stories
## Practical Application
When generating hypotheses:
1. **Draft initial hypotheses** focusing on mechanistic explanations
2. **Apply quality criteria** to identify weaknesses
3. **Refine hypotheses** to improve testability and clarity
4. **Develop specific predictions** to enhance testability and falsifiability
5. **Compare systematically** across all criteria
6. **Prioritize for testing** based on distinguishability and feasibility
Remember: The goal is not a perfect hypothesis, but a set of testable, falsifiable, informative hypotheses that advance understanding of the phenomenon.

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# Literature Search Strategies
## Effective Techniques for Finding Scientific Evidence
Comprehensive literature search is essential for grounding hypotheses in existing evidence. This reference provides strategies for both PubMed (biomedical literature) and general scientific search.
## Search Strategy Framework
### Three-Phase Approach
1. **Broad exploration:** Understand the landscape and identify key concepts
2. **Focused searching:** Target specific mechanisms, theories, or findings
3. **Citation mining:** Follow references and related articles from key papers
### Before You Search
**Clarify search goals:**
- What aspects of the phenomenon need evidence?
- What types of studies are most relevant (reviews, primary research, methods)?
- What time frame is relevant (recent only, or historical context)?
- What level of evidence is needed (mechanistic, correlational, causal)?
## PubMed Search Strategies
### When to Use PubMed
Use WebFetch with PubMed URLs for:
- Biomedical and life sciences research
- Clinical studies and medical literature
- Molecular, cellular, and physiological mechanisms
- Disease etiology and pathology
- Drug and therapeutic research
### Effective PubMed Search Techniques
#### 1. Start with Review Articles
**Why:** Reviews synthesize literature, identify key concepts, and provide comprehensive reference lists.
**Search strategy:**
- Add "review" to search terms
- Use PubMed filters: Article Type → Review, Systematic Review, Meta-Analysis
- Look for recent reviews (last 2-5 years)
**Example searches:**
- `https://pubmed.ncbi.nlm.nih.gov/?term=wound+healing+diabetes+review`
- `https://pubmed.ncbi.nlm.nih.gov/?term=gut+microbiome+cognition+systematic+review`
#### 2. Use MeSH Terms (Medical Subject Headings)
**Why:** MeSH terms are standardized vocabulary that captures concept variations.
**Strategy:**
- PubMed auto-suggests MeSH terms
- Helps find papers using different terminology for same concept
- More comprehensive than keyword-only searches
**Example:**
- Instead of just "heart attack," use MeSH term "Myocardial Infarction"
- Captures papers using "MI," "heart attack," "cardiac infarction," etc.
#### 3. Boolean Operators and Advanced Syntax
**AND:** Narrow search (all terms must be present)
- `diabetes AND wound healing AND inflammation`
**OR:** Broaden search (any term can be present)
- `(Alzheimer OR dementia) AND gut microbiome`
**NOT:** Exclude terms
- `cancer treatment NOT surgery`
**Quotes:** Exact phrases
- `"oxidative stress"`
**Wildcards:** Variations
- `gene*` finds gene, genes, genetic, genetics
#### 4. Filter by Publication Type and Date
**Publication types:**
- Clinical Trial
- Meta-Analysis
- Systematic Review
- Research Support, NIH
- Randomized Controlled Trial
**Date filters:**
- Recent work (last 2-5 years): Cutting-edge findings
- Historical work: Foundational studies
- Specific time periods: Track development of understanding
#### 5. Use "Similar Articles" and "Cited By"
**Strategy:**
- Find one highly relevant paper
- Click "Similar articles" for related work
- Use cited by tools to find newer work building on it
### PubMed Search Examples by Hypothesis Goal
**Mechanistic understanding:**
```
https://pubmed.ncbi.nlm.nih.gov/?term=(mechanism+OR+pathway)+AND+[phenomenon]+AND+(molecular+OR+cellular)
```
**Causal relationships:**
```
https://pubmed.ncbi.nlm.nih.gov/?term=[exposure]+AND+[outcome]+AND+(randomized+controlled+trial+OR+cohort+study)
```
**Biomarkers and associations:**
```
https://pubmed.ncbi.nlm.nih.gov/?term=[biomarker]+AND+[disease]+AND+(association+OR+correlation+OR+prediction)
```
**Treatment effectiveness:**
```
https://pubmed.ncbi.nlm.nih.gov/?term=[intervention]+AND+[condition]+AND+(efficacy+OR+effectiveness+OR+clinical+trial)
```
## General Scientific Web Search Strategies
### When to Use Web Search
Use WebSearch for:
- Non-biomedical sciences (physics, chemistry, materials, earth sciences)
- Interdisciplinary topics
- Recent preprints and unpublished work
- Grey literature (technical reports, conference proceedings)
- Broader context and cross-domain analogies
### Effective Web Search Techniques
#### 1. Use Domain-Specific Search Terms
**Include field-specific terminology:**
- Chemistry: "mechanism," "reaction pathway," "synthesis"
- Physics: "model," "theory," "experimental validation"
- Materials science: "properties," "characterization," "synthesis"
- Ecology: "population dynamics," "community structure"
#### 2. Target Academic Sources
**Search operators:**
- `site:arxiv.org` - Preprints (physics, CS, math, quantitative biology)
- `site:biorxiv.org` - Biology preprints
- `site:edu` - Academic institutions
- `filetype:pdf` - Academic papers (often)
**Example searches:**
- `superconductivity high temperature mechanism site:arxiv.org`
- `CRISPR off-target effects site:biorxiv.org`
#### 3. Search for Authors and Labs
**When you find a relevant paper:**
- Search for the authors' other work
- Find their lab website for unpublished work
- Identify key research groups in the field
#### 4. Use Google Scholar Approaches
**Strategies:**
- Use "Cited by" to find newer related work
- Use "Related articles" to expand search
- Set date ranges to focus on recent work
- Use author: operator to find specific researchers
#### 5. Combine General and Specific Terms
**Structure:**
- Specific phenomenon + general concept
- "tomato plant growth" + "bacterial promotion"
- "cognitive decline" + "gut microbiome"
**Boolean logic:**
- Use quotes for exact phrases: `"spike protein mutation"`
- Use OR for alternatives: `(transmissibility OR transmission rate)`
- Combine: `"spike protein" AND (transmissibility OR virulence) AND mutation`
## Cross-Database Search Strategies
### Comprehensive Literature Search Workflow
1. **Start with reviews (PubMed or Web Search):**
- Identify key concepts and terminology
- Note influential papers and researchers
- Understand current state of field
2. **Focused primary research (PubMed):**
- Search for specific mechanisms
- Find experimental evidence
- Identify methodologies
3. **Broaden with web search:**
- Find related work in other fields
- Locate recent preprints
- Identify analogous systems
4. **Citation mining:**
- Follow references from key papers
- Use "cited by" to find recent work
- Track influential studies
5. **Iterative refinement:**
- Add new terms discovered in papers
- Narrow if too many results
- Broaden if too few relevant results
## Topic-Specific Search Strategies
### Mechanisms and Pathways
**Goal:** Understand how something works
**Search components:**
- Phenomenon + "mechanism"
- Phenomenon + "pathway"
- Phenomenon + specific molecules/pathways suspected
**Examples:**
- `diabetic wound healing mechanism inflammation`
- `autophagy pathway cancer`
### Associations and Correlations
**Goal:** Find what factors are related
**Search components:**
- Variable A + Variable B + "association"
- Variable A + Variable B + "correlation"
- Variable A + "predicts" + Variable B
**Examples:**
- `vitamin D cardiovascular disease association`
- `gut microbiome diversity predicts cognitive function`
### Interventions and Treatments
**Goal:** Evidence for what works
**Search components:**
- Intervention + condition + "efficacy"
- Intervention + condition + "randomized controlled trial"
- Intervention + condition + "treatment outcome"
**Examples:**
- `probiotic intervention depression randomized controlled trial`
- `exercise intervention cognitive decline efficacy`
### Methods and Techniques
**Goal:** How to test hypothesis
**Search components:**
- Method name + application area
- "How to measure" + phenomenon
- Technique + validation
**Examples:**
- `CRISPR screen cancer drug resistance`
- `measure protein-protein interaction methods`
### Analogous Systems
**Goal:** Find insights from related phenomena
**Search components:**
- Mechanism + different system
- Similar phenomenon + different organism/condition
**Examples:**
- If studying plant-microbe symbiosis: search `nitrogen fixation rhizobia legumes`
- If studying drug resistance: search `antibiotic resistance evolution mechanisms`
## Evaluating Source Quality
### Primary Research Quality Indicators
**Strong quality signals:**
- Published in reputable journals
- Large sample sizes (for statistical power)
- Pre-registered studies (reduces bias)
- Appropriate controls and methods
- Consistent with other findings
- Transparent data and methods
**Red flags:**
- No peer review (use cautiously)
- Conflicts of interest not disclosed
- Methods not clearly described
- Extraordinary claims without extraordinary evidence
- Contradicts large body of evidence without explanation
### Review Quality Indicators
**Systematic reviews (highest quality):**
- Pre-defined search strategy
- Explicit inclusion/exclusion criteria
- Quality assessment of included studies
- Quantitative synthesis (meta-analysis)
**Narrative reviews (variable quality):**
- Expert synthesis of field
- May have selection bias
- Useful for context and framing
- Check author expertise and citations
## Time Management in Literature Search
### Allocate Search Time Appropriately
**For straightforward hypotheses (30-60 min):**
- 1-2 broad review articles
- 3-5 targeted primary research papers
- Quick web search for recent developments
**For complex hypotheses (1-3 hours):**
- Multiple reviews for different aspects
- 10-15 primary research papers
- Systematic search across databases
- Citation mining from key papers
**For contentious topics (3+ hours):**
- Systematic review approach
- Identify competing perspectives
- Track historical development
- Cross-reference findings
### Diminishing Returns
**Signs you've searched enough:**
- Finding the same papers repeatedly
- New searches yield mostly irrelevant papers
- Sufficient evidence to support/contextualize hypotheses
- Multiple independent lines of evidence converge
**When to search more:**
- Major gaps in understanding remain
- Conflicting evidence needs resolution
- Hypothesis seems inconsistent with literature
- Need specific methodological information
## Documenting Search Results
### Information to Capture
**For each relevant paper:**
- Full citation (authors, year, journal, title)
- Key findings relevant to hypothesis
- Study design and methods
- Limitations noted by authors
- How it relates to hypothesis
### Organizing Findings
**Group by:**
- Supporting evidence for hypothesis A, B, C
- Methodological approaches
- Conflicting findings requiring explanation
- Gaps in current knowledge
**Synthesis notes:**
- What is well-established?
- What is controversial or uncertain?
- What analogies exist in other systems?
- What methods are commonly used?
## Practical Search Workflow
### Step-by-Step Process
1. **Define search goals (5 min):**
- What aspects of phenomenon need evidence?
- What would support or refute hypotheses?
2. **Broad review search (15-20 min):**
- Find 1-3 review articles
- Skim abstracts for relevance
- Note key concepts and terminology
3. **Targeted primary research (30-45 min):**
- Search for specific mechanisms/evidence
- Read abstracts, scan figures and conclusions
- Follow most promising references
4. **Cross-domain search (15-30 min):**
- Look for analogies in other systems
- Find recent preprints
- Identify emerging trends
5. **Citation mining (15-30 min):**
- Follow references from key papers
- Use "cited by" for recent work
- Identify seminal studies
6. **Synthesize findings (20-30 min):**
- Summarize evidence for each hypothesis
- Note patterns and contradictions
- Identify knowledge gaps
### Iteration and Refinement
**When initial search is insufficient:**
- Broaden terms if too few results
- Add specific mechanisms/pathways if too many results
- Try alternative terminology
- Search for related phenomena
- Consult review articles for better search terms
**Red flags requiring more search:**
- Only finding weak or indirect evidence
- All evidence comes from single lab or source
- Evidence seems inconsistent with basic principles
- Major aspects of phenomenon lack any relevant literature
## Common Search Pitfalls
### Pitfalls to Avoid
1. **Confirmation bias:** Only seeking evidence supporting preferred hypothesis
- **Solution:** Actively search for contradicting evidence
2. **Recency bias:** Only considering recent work, missing foundational studies
- **Solution:** Include historical searches, track development of ideas
3. **Too narrow:** Missing relevant work due to restrictive terms
- **Solution:** Use OR operators, try alternative terminology
4. **Too broad:** Overwhelmed by irrelevant results
- **Solution:** Add specific terms, use filters, combine concepts with AND
5. **Single database:** Missing important work in other fields
- **Solution:** Search both PubMed and general web, try domain-specific databases
6. **Stopping too soon:** Insufficient evidence to ground hypotheses
- **Solution:** Set minimum targets (e.g., 2 reviews + 5 primary papers per hypothesis aspect)
7. **Cherry-picking:** Citing only supportive papers
- **Solution:** Represent full spectrum of evidence, acknowledge contradictions
## Special Cases
### Emerging Topics (Limited Literature)
**When little published work exists:**
- Search for analogous phenomena in related systems
- Look for preprints (arXiv, bioRxiv)
- Find conference abstracts and posters
- Identify theoretical frameworks that may apply
- Note the limited evidence in hypothesis generation
### Controversial Topics (Conflicting Literature)
**When evidence is contradictory:**
- Systematically document both sides
- Look for methodological differences explaining conflict
- Check for temporal trends (has understanding shifted?)
- Identify what would resolve the controversy
- Generate hypotheses explaining the discrepancy
### Interdisciplinary Topics
**When spanning multiple fields:**
- Search each field's primary databases
- Use field-specific terminology for each domain
- Look for bridging papers that cite across fields
- Consider consulting domain experts
- Translate concepts between disciplines carefully
## Integration with Hypothesis Generation
### Using Literature to Inform Hypotheses
**Direct applications:**
- Established mechanisms to apply to new contexts
- Known pathways relevant to phenomenon
- Similar phenomena in related systems
- Validated methods for testing
**Indirect applications:**
- Analogies from different systems
- Theoretical frameworks to apply
- Gaps suggesting novel mechanisms
- Contradictions requiring resolution
### Balancing Literature Dependence
**Too literature-dependent:**
- Hypotheses merely restate known mechanisms
- No novel insights or predictions
- "Hypotheses" are actually established facts
**Too literature-independent:**
- Hypotheses ignore relevant evidence
- Propose implausible mechanisms
- Reinvent already-tested ideas
- Inconsistent with established principles
**Optimal balance:**
- Grounded in existing evidence
- Extend understanding in novel ways
- Acknowledge both supporting and challenging evidence
- Generate testable predictions beyond current knowledge