An observational study is a study in which the investigator cannot control the assignment of treatment to subjects because the participants or conditions are not directly assigned by the researcher.
In an experimental study, the investigators directly manipulate or assign participants to different interventions or environments
Experimental studies that involve humans are called clinical trials. They fall into two categories: those with controls, and those without controls.
Definitions taken from: White SE. Basic & Clinical Biostatistics. 5th ed. New York, N.Y: McGraw-Hill Education LLC; 2020.Retrieved April 21, 2022 from AccessMedicine
Levels of Evidence Pyramid created by Andy Puro, September 2014
Not all resources are available at the KansasCOM Library. Check with Library staff for assistance or visit the full database list.
Study Design 101: Himmelfarb's tutorial on study types and how to find them
Study Designs (Centre for Evidence Based Medicine, University of Oxford)
Learn about Clinical Studies (ClinicalTrials.gov, National Institutes of Health)
Study Designs Guide (Deakin University)