Variables are anything that can either be measured or controlled in an experiment. There’s three types of variables; Independent, Dependent and Controlled. What these mean varies from lab to lab.
Independent Variable: This is the variable that will be changed, and the amount and how it is changed is known to the researcher.
In a biology lab this could be the concentration of a chemical solution added to a medium, in a chemistry lab it could be the temperature of the reaction, and in a neuroscience lab the dosage of a drug administered to a test animal.
Dependent Variable: The result of the independent variable. It’s the effect on the subject, measured in a known unit.
In a biology lab, it can be the rate of growth measured over time after the addition of the chemical, a chemistry lab it can be the rate of the reaction (how quickly the reaction is happening, measured by the change in color, amount of gas produced, product created etc) and the neuroscience lab it can be brain activity (measured by using EEG or other imaging techniques)
Controlled Variable: This is the thing that DOES NOT change. This is to make sure that what you’re measuring (The dependent variable) is BECAUSE OF what you’ve done (the independent variable)
In a biology lab this could be what the chemical was added too, the type of cell used. In a chemistry lab this could be the concentration of the chemicals used, and in a neuroscience lab this could be the species of test animal used, time of day testing or the environmental conditions of the testing area.
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