What type of variable is manipulated in a scientific experiment?

In a scientific experiment, the variable that is manipulated by the researcher to observe its effect on another variable is known as the independent variable. This is the factor that the experimenter changes intentionally to test its impact on the dependent variable, which is the outcome being measured. For example, in an experiment examining the effects of different amounts of sunlight on plant growth, the amount of sunlight would be the independent variable because it is the condition being altered.

The term "treatment" can sometimes refer to a specific level or condition of the independent variable, especially in the context of experiments involving different groups receiving different interventions. However, the more precise and universally accepted term for the variable that is manipulated remains the independent variable. This designation helps clarify discussions about experiment design and the relationships between variables being studied.