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Medical Literature: Methodology Matters

Randomized Controlled Trials: The Methodology

As opposed to observational studies, randomized controlled trials are experimental or interventional.

"A controlled trial means that study participants are split into two groups: One group is given the treatment and the other (the control group) is not. The control group may be given a placebo that mimics the actual treatment, but does not contain the treatment being tested... If the treatment and control groups are similar at the start of the study but end up with different outcomes, the treatment is the most likely cause. The randomized-controlled trial allows researchers to rule out alternative explanations."
-McLaren, Z. (2023). What is a clinical trial? A health policy expert explains (May 2020). In The Conversation (Ed.), The Conversation: An Independent Source of Analysis from Academic Researchers.

*Note it is not always possible or ethical to conduct a randomized controlled trial. For example, it would not be ethical to expose children to secondhand smoke to determine its effects on their development. In cases like this, scientists use observational studies (see tab to the left). 

 

How to Find Randomized Controlled Trials

Select the "randomized controlled trial" filter to the left of your search results, or search Clinical Queries:

 

Clinical Queries link in PubMed interface

 

Enter your search term(s), select "clinical studies," then choose the type of question you are asking (are you looking for trials that address therapy, diagnosis, etiology, or prognosis?).

 

PubMed Clinical Queries search

Please note that you can locate randomized controlled trials in most databases the Grinnell College Libraries subscribes to; please contact a librarian if you would like additional assistance.