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Study Designs - Coggle Diagram

- - - - Intervention group become control after washout period; control group become intervention group after washout period.
    - - Randermisation at cluster level e.g. school, village or hospital
    - - More than one intervention
        
        acyclovir in Bell’s Palsy
  - - - Safety issues, pharmacokinetics and dose–response characteristics.
    - - Evidence of activity or optimal dosage
    - - Against standard treatment for noninferiority
    - - Assess long-term safety data
  - - - Publication Bias
      - Time lag bias
- - - - Probability sampling
        
        Simple random sampling
        
        Systematic sampling
        
        Stratified sampling
        
        Cluster sampling
        
        Multi-stage sampling
      - Non-response bias
- - - - Ecological
      - Cross-sectional
        
        ‘Snapshot’ of the population
        
        for describing prevalence and distribution of heath occurrences
      - Case-control
        
        Compare the 'cases' with controls
        
        Relatively inexpensive
        
        Useful for studying rare diseases
      - Cohort
        
        Individuals free of disease
        
        Non-randomized
        
        prospective, retrospective and ambi-directional cohort studies Prospective
    - - RCT
        
        Randomization - Blinding - Placebo (control)
  - - - Cross-sectional
        
        Sensitivity, Specificity, Positive predictive value (PPV), Negative predictive value (NPV)
    - - Cohort - natural course of a disease
    - - Study of causes of disease - Case-control, Cohort or RCT
    - - To measure the effects of therapy -RCT
- - - - Due to lack of concealment of allocation
      - Due to attrition and differential losses
    - - Participant response bias (due to lack of blinding)
      - Outcome ascertainment bias (due to lack of blinding)
    - - Publication bias
      - Time lag bias
      - Outcome reporting bias