What is the definition of an independent variable in research?

The definition of an independent variable in research is accurately captured by the statement that describes it as a variable that is changed by the researcher. This means that the independent variable is manipulated or altered intentionally to observe how it affects another variable, known as the dependent variable. By varying the independent variable, researchers can assess its impact on the outcomes being measured.

This concept is fundamental in experimental design, as it allows scientists to establish cause-and-effect relationships. For example, if a researcher is studying the effect of different amounts of sunlight on plant growth, the amount of sunlight would be the independent variable, while the growth of the plants would be the dependent variable.

The other options do not correctly define an independent variable. A variable that remains constant during the experiment refers to a control or constant variable, while a variable that is measured as a response is specifically the dependent variable. Lastly, the notion of a variable that dictates the outcome of the experiment is too vague and does not accurately describe the independent variable's role within the experimental framework.