Which variable is manipulated or tested during an experiment?

In an experiment, the variable that is manipulated or tested is known as the independent variable. This is the factor that researchers change intentionally to observe its effect on another variable, typically the dependent variable. By manipulating the independent variable, researchers can determine whether there is a cause-and-effect relationship between the two. For example, if an experiment is designed to assess the impact of different amounts of sunlight on plant growth, the amount of sunlight will be the independent variable manipulated by the researcher.

The independent variable is crucial for experimental design as it allows scientists to control and understand how changes in one aspect of the situation can lead to changes in another, providing insights into causal relationships. Understanding this manipulation is fundamental to conducting rigorous scientific research.