The image is taken from the book, Essentials of Evidence-Based Nursing Practice, p.23 (2018). It shows that the strongest evidence at the top, is systematic reviews, "because the strongest evidence comes from careful syntheses of multiple studies (23)."
The AUTHOR did the research, conducted the study, or ran the experiment; Includes the hypothesis, methodology, and results sections
The AUTHOR did NOT do the study/experiment her/himself.
3 places an article will mention what type of study was done:
Systematic Review
Uses explicit, rigorous methods to identify, critically appraise, and synthesize multiple studies on a topic (the strongest type of evidence).
Meta Analysis
A type of systematic review, that uses a quantitative method to statistically combine the results of many studies and synthesize their conclusions together.
Randomized controlled trial
A clinical trial that involves at least one test treatment and one control treatment, concurrent enrollment and follow up of the test- and control-treated groups, and in which the treatments to be administered are selected by a random process.
Prospective, blind comparison to a gold standard
A controlled trial that compares a new diagnostic tool/test to what is currently considered the "goal standard."
Cohort Study
Study in which subsets of a defined population are identified and studies over a period of time to see the effects of something.
Case Control Studies
Study uses cases with a certain condition, such as kidney disease, and compares it to control cases without the condition.
Case Series / Reports
Articles written about one patient or a series of patients with the same issue. Great for rare diseases, disorders, and drug/treatment reactions (Not the best source of evidence because it focuses on a small group of people).