What is the variable that is presumed to have an effect on another variable?

The independent variable is the factor that is presumed to have an effect on another variable, often referred to as the dependent variable. In research, the independent variable is manipulated or changed to observe how it influences the dependent variable. This relationship allows researchers to establish cause-and-effect dynamics within their studies. For example, if a study is investigating the effect of a new medication on blood pressure, the medication would be the independent variable, as it is the condition being altered, while blood pressure represents the dependent variable being measured to assess the impact of the change.

In contrast, the dependent variable depends on the independent variable, since its value is expected to change in response to the manipulations of the independent variable. Controlled variables are those that are kept constant to avoid their influence on the outcomes of the experiment, while confounding variables are external influences that might obscure the results by affecting the dependent variable unpredictably. Understanding the role of the independent variable is crucial for designing experiments and interpreting their results effectively.