What is a Clinical Study? - Definition & Explanation

Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

Clinical studies help scientists and medical professionals discover and test new treatments. Learn more about the definition, importance and process of clinical studies and test your knowledge with a quiz.


In 1537, Ambroise Paré was treating soldiers injured in battle. He knew that pouring boiling oil onto a wound would prevent infection, but he didn't have enough oil for all of the soldiers. He mixed together egg yolks, rose oil, and turpentine then applied it to some of the soldiers' wounds. The next day, he found that the new mixture worked as well as the boiling oil, without the side effects of burns and pain that the oil produced. Paré's discovery was made through the use of a clinical study.

Ambroise Pare
Photo of Ambroise Paré

A clinical study is a scientific examination of how a treatment for an illness or mental disorder works in humans.

Importance of Clinical Studies

Clinical studies (also called clinical trials) help scientists and doctors discover the best treatment for an illness or disorder. Imagine that Paré hadn't done a clinical trial of his concoction: we might still be pouring boiling oil on patients today!

In addition to helping scientists figure out what treatment works best, clinical studies help them find out the side effects of a treatment. Drugs are often tested on animals first. However, animals might not suffer from the same side effects that humans do. Clinical trials will help scientists discover important (and sometimes deadly) side effects.

Conducting a Clinical Study

The foundation of a clinical study is its participants, who are volunteers and may or may not be compensated for their participation. All clinical studies have possible negative effects: a drug to treat bipolar disorder might cause kidney damage; a new therapy program to treat depression might cause emotional pain. To protect the study's volunteers, researchers must get approval for the study plan and informed consent from the study volunteers.

Before the study begins, researchers must get approval for their study by an Institutional Review Board (IRB). The IRB is a group of scientists and community members which examines the plan for a study and approves it. They weigh the possible negative effects of the study with the possible benefits and makes sure that the dangers have been minimized. Once the IRB approves a study, the researchers can begin recruiting participants. When a person volunteers for a study, the scientists running the study are required to inform the volunteers of any side effects that they might experience.

Once a pool of participants gives their informed consent, the researchers must group them and conduct the study. Let's say that we want to conduct a study to show that taking boxing lessons can effectively treat survivors of rape. We have 100 volunteers, and we need to break them into two groups: one that will take boxing lessons (the experimental group) and one that won't (the control group). At the end of the study, we will compare the results of the experimental group to the results of the control group to see if the boxing lessons help. Because we have 100 volunteers, each group should have 50 participants. In an ideal study, we will assign them to the groups randomly, and the participants will not know what group they are in. This is called randomization.

Breaking Participants into Groups
Chart of Example Study Groups

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