Control Group vs. Experimental Group
Key Differences
Comparison Chart
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Number of Groups
Presence of Group
Other Names
Independent Variable
Role
Type of Hypothesis
Involvement in Experiment
Control Group vs. Experimental Group
Research is an ideal source for scientific investigation. During the research, tests are conducted under controlled conditions to find out the validity of a hypothesis. The different numbers and types of groups are planned according to the topic. Two main types of groups are the control group and the experimental group.
The control group is the group that is not directly involved in the experiment but is used to compare the results with the experimental group. On the other hand, the experimental group is the group in which we are conducting experiment. So, all the experiments do not need a control group, but, all the experiments have an experimental group.
A control group is a group in which the independent variable is not changing or set as a standard value by the researcher. On the flip side, the researcher changes that independent variable in the experimental group that may affect the dependent variable. A control group is exactly identical to the experimental group except for the change in experimental conditions.
A control group is a group that is used to compare the results of the experimental group with the natural results of the control group and increases the validity and reliability of the results. On the other side, the experimental group explains the influence of the independent variable on the dependent variable.
If there is no any change in the value of dependent variables after comparing the results of the experimental group with the natural group then the null hypothesis is accepted whereas, if there is a significant change in the dependent variable of the control group and the experimental group than an alternative hypothesis is accepted.
An experiment has only one control group, but it may have more than one experimental group. All the experiments do not have a control group, but, the experiments that are with a control group are called controlled experiments.
What is the Control Group?
In an experiment, a control group is a group that does not receive variables that are to be tested. A control group is also known as the comparison group. All the experiments do not have a control group, but, the experiments that are with this group are called controlled experiments. When the experimental conditions are difficult to isolate, control groups are very important.
In this type of group, the independent variable is not changing or set as a standard value by the researcher. It is used to compare the results of the experimental group with the natural results of the control group and increases the validity and reliability of the results. If there is no change in the value of dependent variables after comparing the results of the experimental group with the natural group then the null hypothesis is accepted.
Example
An example of a controlled experiment is such that if anyone wants to know that plants need water to live or not, he will design an experiment. In the experiment, a plant will water, and others will not, to check the necessity of water for its survival. The watered plant will be from the experimental group. On the other side, that one which is not watered is known as the control group.
Types
- Positive Control Group: A type of control group in which the experiment is designed in such a way that positive result is guaranteed is called positive control group. For Example, a researcher is planning an experiment to check the bacterial susceptibility to a drug. He will use a positive control to confirm that the growth medium is able to support bacteria. He would grow known bacteria to carry the drug resistance marker, so they would be able to survive on a drug-treated medium. Group will be positive control if the growth of the bacteria takes place. It shows that other bacteria that are drug-resistant should also be able to survive the test.
- Negative Control group: A type of control group in which experimental conditions are designed in such a way that it will cause negative results is called a negative control group. These types of groups are very common in science experiments to tell the students how to find out the independent variable. For example, a researcher wants to know either a new fertilizer has any effect on plant growth or not. He will design a negative control group in which plants will be grown without the fertilizer but under the same conditions as the experimental group. He could design several groups by varying the concentration of fertilizer. If the fertilizer does not have any effect on the plant growth, then it will be a null hypothesis. But, if there is a difference in the growth rate of plants, then there will be a strong correlation between the growth and the fertilizer. Keep in mind that the fertilizer may have a negative effect on growth, or there will be no growth at all due to some reasons.
What is the Experimental Group?
An experimental group is a group that receives variables that are to be tested. All the experiments have one or more experimental groups. The researcher changes the independent variable in the experimental group that may affect the dependent variable in research.
The experimental group explains the influence of the independent variable on the dependent variable. If there is a significant transformation in the dependent variable of the control group and the experimental group, then the alternative hypothesis is accepted.
Two points should be kept in mind while setting an experimental group, i.e., the variable that is to be tested should be clearly defined and you should also know the procedure to find the results from the experimental group.
There should be a way of making a comparison to measure the results. Results could be obtained by comparing the results of the experimental group with the control group. Only one variable can be find out in an experimental group at a time. Because, if we are taking more then one variable per group, we would not be able to find out which one is responsible for the results.
Example
A person wants to find out that either a popcorn pops better if it is placed in a refrigerator before placing it in the microwave or not. To check this hypothesis, he will placed one bag of popcorns in refrigerator and other in the kitchen cabinet as usual for one night. Next day he will pop both bags in the microwave and compare the results to check the validity of his hypothesis. Here, a bag of popcorns that was placed in the refrigerator is an experimental group, and that one which is placed in a kitchen cabinet is a control group.
