People use experiments to help understand cause and effect in everyday life. What this really means is that people create and experiment so that they can change only one thing within the experiment in order to find out how it will create a change. The item or “thing” that the person is changing is called the variable.
A variable is the item, trait or condition that can occur or happen in different amounts. When a person does an experiment there are usually three kinds of variables. These variables are known as independent, dependent and controlled variables.
This is the item or thing that is changed by the person doing the test.
In a quality experiment there is only ONE independent variable. This way the person can observe exactly how that one thing (independent variable) affects the outcome.
Independent variables are changes that are specifically caused by you the experimenter.
This is the “thing” item or outcome that the person is measuring or observing. The new measurement of the dependent variable is caused by and depends on how much (the value) of the independent variable.
Dependent variables are changes that occur due to the independent variable being introduced into the experiment.
The controlled variables are “things” that the experimenter wants to remain the same and constant throughout the experiment.
A controlled variable is all other things that are kept constant so that they do not have an affect or influence on the dependent variable.
Control Group:
This is a group that is not being experimented on and is called the control group. The reason that this group is not being exposed to the independent variable is so that you can compare your experimental results back to this group. Simply said it is so you can compare the group that has changed to the group that stayed the same. All quality science experiments use a control group.
Experimental Group:
The expeimental group is the group that recieves a treatment or has been exposed to something. In other words the scientist has changed an independent variable and makes observations for dependent variables.