In an experiment, what is the factor of interest called?
In an experiment, there are several factors of interest.
One of them is the factor that you can change.
It is often called the independent variable because you can change it as you want.
You hold all other factors (the control variables) constant.
Then you vary the independent variable to get information about how it affects another factor called the dependent variable or the response variable.
For example, if you wanted to find the effect of temperature on a gas, you would hold the mass of gas and its pressure (the control variables) constant.
Then you would vary the temperature (the independent variable) and see what effect it has on the volume of the gas (the dependent variable).