The independent variables, are the factors that are tested by being varied by the experimenter.
When conducting experiments, one needs to deal with variables, those factors or elements that are likely to vary or change. A typical study has an independent variable and a dependent variable.
The independent variable, also known as manipulated variable, is something that the experimenter purposely changes or varies over the course of the investigation. The dependent (or responding) variable is the one that is observed and likely changes in response to the independent variable.