What is an independent variable?

An independent variable is a key concept in experimental research and is characterized by its role as the factor that is manipulated by the researcher to determine its effect on other variables. This manipulation allows researchers to observe changes and establish cause-and-effect relationships. In experimental design, the independent variable is altered while the other variables (often referred to as dependent variables) are measured to assess how changes in the independent variable influence them. This is foundational in research, as it helps to isolate the impact of specific factors, thereby contributing to the validity and reliability of the results gathered.

In contrast, the other options describe different roles that variables can play in research but do not accurately define what an independent variable is. For example, a variable that remains constant refers to a controlled variable, while a variable that is measured but not manipulated highlights the nature of dependent variables. Lastly, a variable that controls experiments doesn't align with the definition of an independent variable, as it suggests a broader role in the experimental design rather than the specific manipulation required to assess the effects on dependent variables.