Classification of Studies
Hierarchy and Classification of Research StudiesPrimary Reports | Secondary Reports | ||
A
|
Randomized Controlled Trial Cluster Randomized Trial Randomized Crossover Trial |
M
|
Meta-analysis or Systematic review Decision analysis Cost-benefit analysis Cost-effectiveness study |
B | Prospective Cohort Study Retrospective Cohort Study |
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C | Non-Randomized Controlled Trial Non-Randomized Crossover Trial Case-Control Study Time Series Study Diagnostic, Validity or Reliability Study |
R | Narrative review (Review article) Consensus statement Consensus report |
D | Non-Controlled Trial Case Study or Case Series Other Descriptive Study Cross-Sectional Study Trend Study Before-After Study |
X | Medical opinion |