control group

American  

[kuhn-trohl groop] / kənˈtroʊl ˌgrup /

noun

1. (in an experiment or clinical trial) a group of subjects closely resembling the treatment group in many demographic variables but not receiving the active medication or factor under study and thereby serving as a comparison group when treatment results are evaluated.

---

control group British  

noun

1. any group used as a control in a statistical experiment, esp a group of patients who receive either a placebo or a standard drug during an investigation of the effects of another drug on other patients

---

Etymology

Origin of control group

First recorded in 1950–55

Compare meaning

How does control-group compare to similar and commonly confused words? Explore the most common comparisons:

• control group vs. experimental group

Example Sentences

The ASA report said: "We had concerns about the study's methodology, including that there was no control group, nor was there information about how participants were recruited."

From BBC • Apr. 28, 2026

It’s unfeasible to randomly assign hundreds of forests or oceans to become protected areas or a control group.

From Slate • Apr. 28, 2026

By comparison, the control group regained roughly twice as much.

From Science Daily • Apr. 23, 2026

She calls FDA’s demand for a control group “completely unethical” since “they’re progressing on that treatment”—that is, their cancer is getting worse.

From The Wall Street Journal • Apr. 21, 2026

The men experienced reduction in the dopamine transporter, a protein, as compared to a control group of nine men who were not compulsive Internet users.

From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel