Clinical Research Terms Explained
Understanding the terminology used in clinical research helps you better evaluate the quality and significance of HBOT studies.
Evidence Levels
Evidence levels rank the quality and reliability of clinical research from 1 (highest) to 5 (lowest):
Level 1 - Systematic Reviews & Meta-Analyses
Highest quality evidence combining multiple high-quality studies
Level 2 - Randomized Controlled Trials (RCTs)
Well-designed experiments with control groups and randomization
Level 3 - Controlled Studies Without Randomization
Studies with comparison groups but without randomization
Level 4 - Case-Control & Cohort Studies
Observational studies that compare groups over time
Level 5 - Case Reports & Expert Opinion
Individual case descriptions and expert recommendations
Jadad Score
The Jadad Scale rates the quality of randomized controlled trials from 0 to 5 points:
Scoring Criteria
Quality Interpretation
Study Types
Meta-Analysis
Statistical analysis combining results from multiple independent studies
Randomized Controlled Trial (RCT)
Participants randomly assigned to treatment or control groups
Cohort Study
Following groups of people over time to observe outcomes
Case-Control Study
Comparing people with a condition to those without it
Cross-Sectional Study
Observing a population at a single point in time
Case Report
Detailed report of individual patient experiences
Statistical Significance
P-Value
The probability that results occurred by chance alone:
- • p < 0.001: Extremely significant (less than 0.1% chance of being due to chance)
- • p < 0.01: Highly significant (less than 1% chance)
- • p < 0.05: Statistically significant (less than 5% chance)
- • p > 0.05: Not statistically significant
Effect Size
Measures how large the treatment effect actually is, not just whether it exists. Common measures include:
- • Small effect: 0.2 - 0.5
- • Medium effect: 0.5 - 0.8
- • Large effect: > 0.8
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