Gold standard study for Clinical research is
• Meta-analysis (Highest clinical relevance: GOLD STANDARD)
• Systematic review
• Cohort study
• Case control study
• Case series
• Case report
• Ideas, Editorials, Opinions
• Animal research
• In-vitro (test-tube) research (Lowest clinical relevance)
Randomised double-blind trial
Systematic meta-analysis
Ecological study
Retrospective cohort study