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Control Group vs. Experimental Group: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Updated on October 2, 2023
Control group is unaltered during an experiment while experimental group undergoes the variable being tested, ensuring observed effects are due to the variable and not external factors.

Key Differences

The control group in scientific studies is essentially the baseline group, which remains untouched or unexposed to the variable being tested throughout the experiment. It provides a standard of comparison when assessing the outcomes of the experimental group, helping to validate the effects of the variable being tested. Ensuring the control group is consistent and relevant to the experimental conditions is vital to maintaining the integrity of the experiment.
The experimental group is where the key focus of the experiment resides, as it is subject to the variable or intervention being examined. The alterations made to this group are deliberate and strategic, aiming to explore the effects of specific changes or treatments. Comparing the outcomes from the experimental group with those of the control group allows researchers to deduce the impact of the variable being tested, thereby, providing a framework for interpreting the results.
The role of the control group is to be the constant amidst the variability introduced within the experimental group. In a properly designed experiment, the control group and the experimental group should be identical in every way except for the variable being tested. Thus, the control group serves to isolate and affirm the effects of the variable, ensuring that the observed changes in the experimental group are genuinely due to the manipulated variable and not external factors.
In contrast, the experimental group is manipulated in accordance with the research objective. The variability introduced into the experimental group might involve exposure to a certain treatment, condition, or any other intentional modification relevant to the study. By comparing the outcomes from both groups, scientists aim to validate their hypothesis and establish a cause-and-effect relationship between the variable and any observed changes.
It’s worth noting that the precise selection and meticulous management of both the control group and the experimental group are paramount to safeguarding the validity and reliability of the experiment. Meticulously ensuring that both groups are initially identical and that they are treated identically apart from the variable in question underpins the integrity of the entire research study.

Comparison Chart


Serves as a standard for comparison.
Undergoes variations to assess outcomes.

Exposure to

Is not exposed to the variable being tested.
Is exposed to the variable being tested.

Expected Change

No expected change due to the variable.
Expected change due to the variable.

Result Utilization

Used to validate the results of the experiment.
Used to observe potential changes.


Is compared to the experimental group.
Is compared to the control group.

Control Group and Experimental Group Definitions

Control Group

A group in an experiment that does not receive the test variable.
The control group was given a placebo to ensure valid results.

Experimental Group

The group subjected to modifications aimed to test hypotheses.
Results from the experimental group were pivotal for hypothesis validation.

Control Group

The standard to which experimental outcomes are compared.
Researchers analyzed the control group to establish baseline data.

Experimental Group

A subset within a study experiencing intentional variable changes.
The experimental group demonstrated significant alterations post-treatment.

Control Group

A subset within an experiment untouched by independent variables.
The control group received no treatment to maintain constant conditions.

Experimental Group

A group used to observe potential effects of a variable.
Scientists noted varying responses within the experimental group.

Control Group

A non-manipulated group used to validate experimental results.
Observing the control group, scientists noticed no changes in behavior.

Experimental Group

The testing group in a study to ascertain variable impacts.
The experimental group showcased varied outcomes when exposed to the variable.

Control Group

A group that remains unaffected during experimental testing.
The control group showed no alterations, verifying the test’s impact.

Experimental Group

The group in an experiment that is exposed to the variable.
The experimental group was given the new drug for assessment.


What is a control group?

A control group is a group in an experiment that is not exposed to the variable being tested, serving as a baseline for comparison.

Can an experiment have more than one control group?

Yes, an experiment can have multiple control groups to examine different variables or establish varied baselines.

What is an experimental group?

An experimental group is the group in an experiment that is exposed to the variable being tested to observe potential effects.

Why does the experimental group undergo variable testing?

To observe and measure the effects of the variable and to test the hypothesis of the research.

How are participants allocated to control or experimental groups?

Typically, participants are randomly assigned to ensure unbiased distribution and valid results.

What distinguishes the control group from the experimental group?

The control group isn't exposed to the variable being tested, while the experimental group is.

What role does a control group play in scientific research?

The control group provides a stable baseline, allowing researchers to confidently attribute observed changes to the variable applied to the experimental group.

Can an experiment proceed without an experimental group?

Theoretically, yes, but it would not provide information on the effects of the variable, drastically limiting the research's utility and conclusions.

Why is a control group important?

It is essential to validate the results of an experiment by ensuring that any changes observed are due to the variable being tested, not other factors.

Is it possible to have multiple experimental groups in a study?

Yes, researchers can utilize multiple experimental groups to explore varied levels or types of experimental conditions.

How should control and experimental groups be similar or different?

They should be as similar as possible in all aspects except for the variable being tested to ensure accurate comparison.

What happens if an experiment lacks a control group?

Without a control group, it is difficult to ascertain if results from the experimental group are due to the variable or other factors.

What types of variables are typically introduced to experimental groups?

Variables can be anything manipulated in the experiment, such as treatment, condition, time, temperature, etc., depending on the research question.

How is data compared between control and experimental groups?

Data is analyzed to determine if significant differences exist between the groups, attributing any dissimilarities to the variable applied.

Are control groups always necessary in experiments?

While highly recommended for validity, some study designs or constraints might not utilize a control group, depending on the research context.

Can a participant be in both control and experimental groups?

Generally, no, to avoid contamination of results. Each participant is typically assigned to only one group.

Is it possible for a control group to exhibit changes?

Yes, but changes should not result from the experimental variable. Any shift may stem from other factors, which researchers should consider.

What is a placebo, concerning control groups?

A placebo is a neutral intervention, like a sugar pill, given to the control group to ensure participants are unaware of their group assignment, preventing bias.

Can control and experimental groups consist of different types of subjects?

Ideally, no. Both groups should be as identical as possible initially to ensure that the variable is the only difference between them.

How are results validated using experimental and control groups?

By comparing outcomes, if the groups differ significantly post-intervention, researchers may attribute changes to the variable, validating the results.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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