What is the key difference between an experimental group and a control group?

Scientific experiments are often carried out in the form of controlled experiments. The reason why these experimental studies are so called is because of the subjects in the experiment being divided into two groups called the experimental group and the control group. The two groups consist of subjects that are identical in nature. There is so much of similarity that is intentional and deliberate that it is hard to tell the difference between a control group and an experimental group. However, there is one critical difference between the two groups that makes a researcher treat the two groups differentially. Let us find out this difference.

What is a Control Group?

Control group is the group in the scientific experiment that remains away from the research in the sense that it does not get exposure to experimental conditions. There is always a variable that is tested with the changes in the subjects being recorded and analyzed. The subjects in a control group are not exposed to this variable whose effect is being analyzed. These subjects remain untouched with the variable and help explain the changes in the experimental group on account of variable. In fact, the subjects in a control group are important as they rule out any other reasons for changes in the experimental group.

In an experiment where the effects of a medicine are to be tested, the control group does not receive the medication whereas it is administered to the subjects in the experimental group. Thus, the subjects in a control group serve as a comparison tool when the researcher evaluates the effects of the medication.

What is an Experimental Group?

Experimental group in controlled experiments is the group that receives the variable whose effects are being studied. There are experiments where it is difficult to isolate the variable being tested. This requires creation of a control group that does not receive exposure to the variable. Thus, we have subjects for whom nothing happens while there are subjects in the experimental group that are exposed to the variable. This enables the researcher to contrast the subjects, and he can claim the effects to be because of the variable.

What is the difference between Control Group and Experimental Group?

• The scientific experiments known as controlled experiments necessitate the creation of an experimental group and a control group.

• The two groups are almost identical, and there is no difference in composition.

• However, the subjects in the experimental group are exposed to the variable being tested whereas the subjects in the control group remain away from this variable.

• Control group helps to explain the effect of the variable on the subjects in the experimental group as it does not get exposure to the variable.

                                         Experimental group vs Control group

Related concepts:

• Difference between Alternative hypothesis and Null hypothesis
• Difference between dependent and independent variable

Experimental Group

Control Group

It is the group that you are  conducting experiment

It is the group that you are not conducting experiment

The researcher is changing the independent variable  that he thinks will influence the dependent variable

The researcher is not changing the independent variable or set it as a standard value

A good experimental group is identical to the control group in all way except for the difference in the experimental condition (except for the variable that is changing in the experiment)

A good control group is identical to the experimental group in all way except for the difference in the experimental condition (except for the variable that is changing in the experiment)

The effect or influence of independent variable on dependent variable  is determined by comparing the experimental results with the control group

Helps to compare experimental result with non-experimental natural result (control group). It increases the reliability and validity of experimental results

Alternative hypothesis is accepted, if there is a significant difference in the dependent variables (measured or observed) of experimental group and control group

Null hypothesis is accepted, if there is  no significant difference in the dependent variables (measured or observed) of experimental group and control group