What is a controlled variable?

A controlled variable is a factor or condition in an experiment that remains constant throughout the study to ensure that the results are valid and reliable. By keeping these variables unchanged, researchers can isolate the effect of the independent variable on the dependent variable. This is essential for determining causal relationships, as it minimizes the risk of confounding variables influencing the outcome of the experiment.

For example, if a scientist is testing the effect of a new medication on blood pressure, they would ensure that factors like the duration of the study, the environment in which the experiment takes place, and the subjects’ demographics are kept constant for all test subjects. This allows for a clearer understanding of how the medication itself is affecting blood pressure without interference from other changing factors.

In contrast, other options reflect different aspects of experimental design. A variable that is changed in the experiment refers to the independent variable, while the main focus of the research typically corresponds to the dependent variable. A prediction derived from data is associated with hypotheses or conclusions that can arise after analysis rather than the controlled variables themselves.