Introduction > Planning Your Research > Designing Your Experiment > Controls

Controls In science, controls are used in an experiment to determine if the recorded effects are caused by the treatment imposed. Controls are exposed to exactly the same conditions as the experimental subjects, but they are not exposed to the treatment. When pharmaceutical companies are testing new medicines, volunteers are generally split into two groups - the control group given a placebo and the experimental group given the medication. You may have more than one control - in an experiment looking at the effect of rabbit grazing on trees, your treatment may be surrounding the trees with a rabbit-proof fence, one control may be cutting holes in the fence to allow the rabbits through and another control may be removing the fence completely.

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