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.

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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

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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

Specifically, the customers in the treatment group were 3.39% more likely to try different vendors on the site than those in the control group, especially if those vendors had plentiful inventory.

From The Wall Street Journal • Jun. 9, 2026

One new requirement asked for an inhumane placebo control group, to which no physician could agree.

From The Wall Street Journal • May 14, 2026

Participants in the LSM group averaged 7,280 steps per day, while those in the control group averaged 7,180 steps daily.

From Science Daily • May 11, 2026

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

To make the retest results convincing, some non-cheaters were needed as a control group.

From "Freakonomics: A Rogue Economist Explores the Hidden Side of Everything" by Steven D. Levitt